,,bureau ,,of ,,economic ,,geology ,the ,university of ,texas at ,austin ,austin1 ,texas #ghgab ,john ,t4 ,lonsdale1 ,director ,guidebook #b ,,texas ,,fossils3 ,an ,amateur ,collector's ,handbook ,by ,william ,h4 ,matthews ,,iii ,november #aifj ,second ,printing1 ,july #aifc ,third ,printing1 ,august #aifg ,fourth ,printing1 ,june #aiga ,fifth ,printing1 ,november #aigc ,sixth ,printing1 ,april #aigf ,seventh ,printing1 ,november #aigh ,eighth ,printing1 ,september #aiha ,ninth ,printing1 ,august #aihd ,contents ,page ,introduction #a ,what are fossils8 #c ,the study of fossils #d ,paleobotany #d ,invertebrate paleontology #d ,vertebrate paleontology #d ,micropaleontology #d ,preservation of fossils #e ,requirements of fossilization #e ,missing pages in the record #e ,different kinds of fossil preservation #g ,original soft parts of organisms #g ,original hard parts of organisms #g ,calcareous remains #aj ,phosphatic remains #aj ,siliceous remains #aj ,chitinous remains #aj ,altered hard parts of organisms #aj ,carbonization #aj ,petrifaction or permineralization #aj ,replacement or mineralization #aj ,replacement by calcareous material #aa ,replacement by siliceous material #aa ,replacement by iron compounds #aa ,traces of organisms #aa ,molds and casts #aa ,tracks1 trails1 and burrows #ad ,coprolites #ad ,gastroliths #ad ,pseudofossils #ad ,dendrites #ad ,slickensides #af ,concretions #af ,where and how to collect fossils #ag ,collecting equipment #ag ,where to look #ai ,how to collect #bj ,cleaning and preparation of fossils #ba ,how fossils are named #ba ,the science of classification #ba ,the units of classification #bb ,identification of fossils #bc ,use of identification keys #bc ,identification key to main types of invertebrate fossils #bf ,list of ,texas colleges offering geology courses #bg ,cataloging the collection #ca ,how fossils are used #ca ,geologic history #cc ,geologic column and time scale #cc ,the geology of ,texas #cd ,physiography #ce ,trans-,pecos region #ce ,texas ,plains #ce ,high ,plains #ce ,north-central ,plains #cg ,edwards ,plateau #cg ,grand ,prairie #cg ,llano uplift #cg ,gulf ,coastal ,plain #cg ,geology #cg ,precambrian rocks #dj ,paleozoic rocks #dj ,cambrian #dj ,ordovician #dj ,silurian #dj ,devonian #dj ,mississippian #da ,pennsylvanian #da ,permian #da ,mesozoic rocks #db ,triassic #db ,jurassic #db ,cretaceous #db ,cenozoic rocks #dc ,tertiary #dc ,quaternary #dc ,main types of fossils #dd ,plant fossils #dd ,classification of the plant kingdom #dd ,division ,thallophyta #dd ,division ,bryophyta #dd ,division ,tracheophyta #dd ,animal fossils #dh ,phylum ,protozoa #dh ,class ,sarcodina #dh ,order ,foraminifera #dh ,order ,radiolaria #dh ,phylum ,porifera #di ,phylum ,coelenterata #di ,class ,anthozoa #di ,subclass ,zoantharia #ej ,order ,rugosa #ej ,order ,scleractinia #ej ,order ,tabulata #ej ,phylum ,bryozoa #ej ,phylum ,brachiopoda #ed ,class ,inarticulata #ed ,class ,articulata #ef ,phylum ,mollusca #ef ,class ,gastropoda #ei ,class ,pelecypoda #ei ,class ,cephalopoda #ff ,subclass ,nautiloidea #ff ,subclass ,ammonoidea #ge ,subclass ,coleoidea #gh ,order ,belemnoidea #gh ,phylum ,annelida #gh ,phylum ,arthropoda #gh ,subphylum ,trilobitomorpha #gh ,class ,trilobita #gh ,subphylum ,crustacea #hj ,class ,ostracoda #hj ,phylum ,echinodermata #hj ,subphylum ,pelmatozoa #ha ,class ,cystoidea #ha ,class ,blastoidea #ha ,class ,crinoidea #ha ,subphylum ,eleutherozoa #hb ,class ,asterozoa #hb ,subclass ,asteroidea #hb ,subclass ,ophiuroidea #hb ,class ,echinozoa #hb ,subclass ,echinoidea #hb ,subclass ,holothuroidea #he ,phylum ,chordata #he ,subphylum ,hemichordata #he ,class ,graptolithina #he ,subphylum ,vertebrata #hf ,superclass ,pisces #hg ,class ,agnatha #hg ,class ,placodermi #hg ,class ,chondrichthyes #hg ,class ,osteichthyes #hg ,superclass ,tetrapoda #hi ,class ,amphibia #hi ,class ,reptilia #hi ,cotylosaurs #hi ,turtles #hi ,pelycosaurs #hi ,therapsids #hi ,ichthyosaurs #ie ,mosasaurs #ie ,plesiosaurs #ie ,phytosaurs #ie ,crocodiles and alligators #ie ,pterosaurs #ie ,dinosaurs #ie ,order ,saurischia #ig ,suborder ,theropoda #ig ,suborder ,sauropoda #ig ,order ,ornithischia #ig ,suborder ,ornithopoda #ig ,suborder ,stegosauria #ig ,suborder ,ankylosauria #ig ,suborder ,ceratopsia #ajj ,class ,aves #ajj ,class ,mammalia #ajj ,subclass ,allotheria #ajj ,subclass ,theria #ajj ,order ,edentata #ajj ,order ,carnivora #ajb ,order ,pantodonta #ajb ,order ,dinocerata #ajb ,order ,proboscidea #ajb ,order ,perissodactyla #ajd ,horses #ajd ,titanotheres #ajd ,chalicotheres #ajf ,rhinoceroses #ajf ,order ,artiodactyla #ajf ,entelodonts #ajf ,camels #ajf ,books about fossils #ajh ,general works #ajh ,nontechnical and juvenile #ajh ,collecting helps #ajh ,reference works #aji ,selected references on ,texas fossils #aji ,glossary #aaa ,index #aae ,illustrations ,figures-- ,page #a4 ,sketch of a coprolite--fossilized animal excrement #ad #b4 ,sketch of a gastrolith--the gizzard stone of an ancient reptile #ad #c4 ,dendrites--a typical pseudofossil #ad #d4 ,types of symmetry in a fossil coral #bd #e4 ,bilateral symmetry in fossil brachiopod #bd #f4 ,a brachiopod showing specimen number and accompanying label #ca #g4 ,two types of micropaleontological slides #cb #h4 ,typical ,pennsylvanian crinoidal limestone #da #i4 ,typical ,texas ,foraminifera #di #aj4 ,typical radiolarians #di #aa4 ,morphology and principal parts of corals #ej #ab4 ,two types of bryozoans #ej #ac4 ,morphology and principal parts of articulate brachiopods #ed #ad4 ,lingula1 a typical inarticulate brachiopod #ef #ae4 ,kingena wacoensis1 a common ,cretaceous brachiopod #ef #af4 ,morphology and principal parts of gastropod shells #fj #ag4 ,morphology and principal parts of a typical pelecypod shell #fe #ah4 ,morphology and principal parts of the pearly nautilus #ge #ai4 ,characteristic features of the various types of cephalopod sutures #ge #bj4 ,types of typical fossil annelid worms #gh #ba4 ,morphology and principal parts of trilobites #hj #bb4 ,two extinct attached echinoderms1 ,pentremites and ,caryocrinites #ha #bc4 ,typical modern crinoid1 or 8sea lily10 showing principal parts #ha #bd4 ,graptolites #hf #be4 ,sketches of mastodon and mammoth teeth #ajd #bf4 ,two views of a typical fossil horse tooth #ajd ,plates-- ,page #a4 ,geologic time scale ,frontispiece #b4 ,types of fossil preservation #h #c4 ,silicified brachiopods dissolved from ,permian limestones of the ,glass ,mountains1 ,brewster ,county1 ,texas #ab #d4 ,dinosaur tracks in limestone in bed of ,paluxy ,creek near ,glen ,rose1 ,somervell ,county1 ,texas #ae #e4 ,fossil collecting equipment #ah #f-h4 ,fossil identification charts #bh-cj #i4 ,physiographic map of ,texas #cf #aj4 ,geologic map of ,texas #ch-ci #aa4 ,geologic range of the major groups of plants and animals #de #ab4 ,fossil plants--thallophytes and tracheophytes #df #ac4 ,fossil plants--tracheophytes #dg #ad4 ,paleozoic sponges and sponge spicules #ea #ae4 ,pennsylvanian corals #eb #af4 ,cretaceous and ,tertiary corals #ec #ag4 ,pennsylvanian bryozoans and ,cambrian and ,mississippian brachiopods #ee #ah1 #ai4 ,pennsylvanian brachiopods #eg1 #eh #bj4 ,pennsylvanian gastropods #fa #ba4 ,pennsylvanian and ,cretaceous gastropods #fb #bb1 #bc4 ,tertiary gastropods #fc1 #fd #bd4 ,pennsylvanian pelecypods #fg #be-bh4 ,cretaceous pelecypods #fh-ga #bi-ca4 ,tertiary pelecypods #gb-gd #cb4 ,pennsylvanian and ,cretaceous cephalopods #gf #cc4 ,cretaceous cephalopods #gg #cd4 ,fossil arthropods #gi #ce4 ,fossil starfishes1 crinoids1 and holothurian sclerites #hc #cf4 ,cretaceous echinoids #hd #cg4 ,primitive armored fish1 shark teeth1 and conodonts #hh #ch4 ,comparison of the dinosaurs #ij #ci4 ,comparison of ,mesozoic flying and swimming reptiles #ia #dj4 ,pelycosaur1 cotylosaur1 and a primitive amphibian #ib #da4 ,swimming reptiles #ic #db4 ,phytosaur and flying dinosaurs #id #dc4 ,skull of ,phobosuchus1 from ,cretaceous of ,trans-,pecos ,texas #if #dd4 ,saurischian dinosaurs #ih #de4 ,ornithischian dinosaurs #ii #df1 #dg4 ,cenozoic mammals #aja1 #ajc #dh4 ,tertiary mammals #aje #di4 ,cenozoic mammals #ajg ,illustration3 ,plate #a ,,geologic ,,time ,,scale ,,era ,,period ,,epoch ,,characteristic ,,life ,,cenozoic 8,recent ,life0 ,,quaternary #a ,,million ,,years ,recent ,pleistocene ,,tertiary #fd ,,million ,,years ,pliocene ,miocene ,oligocene ,eocene ,paleocene ,,mesozoic 8,middle ,life0 ,,cretaceous #gj ,,million ,,years ,,jurassic #de ,,million ,,years ,,triassic #ej ,,million ,,years ,,paleozoic 8,ancient ,life0 ,,permian #ee ,,million ,,years ,,carboniferous ,,pennsylvanian #cj ,,million ,,years ,,mississippian #ce ,,million ,,years ,,devonian #ee ,,million ,,years ,,silurian #bj ,,million ,,years ,,ordovician #ge ,,million ,,years ,,cambrian #ajj ,,million ,,years ,,precambrian ,,eras ,,proterozoic ,,era ,,archeozoic ,,era ,,approximate ,,age ,,of ,,the ,,earth ,,more ,,than #c ,,billion #cjj ,,million ,,years ,texas ,fossils ,an ,amateur ,collector's ,handbook ,william ,h4 ,matthews ,,iii#a ,,introduction ,almost everyone has seen the fossilized remains of prehistoric plants or animals4 ,these might have been the skeleton of a gigantic dinosaur1 the petrified trunk of an ancient tree1 or the shells of snails or oysters that lived in the great seas that covered ,texas millions of years ago4 ,each year more and more people are learning that these fossils are more than mere curiosities4 ,instead1 they are realizing that a good collection of fossils provides much information about the early history of our earth1 and that fossil collecting can be a most enjoyable1 fascinating1 and rewarding hobby4 ,it is for these people that ,texas ,fossils was written4 ,this publication is primarily an amateur collector's handbook and as such offers many suggestions and aids to those who would pursue the hobby of fossil collecting4 ,it tells1 for example1 what fossils are1 where and how to collect them1 and how they are used4 ,suggestions are made as to how the specimens may be identified and catalogued1 and there are discussions and illustrations of the main types of plant and animal fossils4 ,included also is a simplified geologic map of ,texas and a brief review of the geology of the ,state4 ,texas ,fossils is not a comprehensive study of the paleontology of ,texas4 ,rather1 it deals primarily with the more common species that the average collector is likely to find4 ,these fossils are illustrated in the plates and figures1 and these illustrations should be of some help in identifying the specimens in one's collection4 ,included for completeness1 however1 are sketches and descriptions of some of the more rare and unusual fossils1 and1 for general interest1 there are illustrations and descriptions of many of the extinct reptiles and mammals that once inhabited this ,state4 ,in addition1 a group of selected references has been included for the reader who wishes to know more about earth history and paleontology4 ,many of these publications provide references of a more technical nature for the more advanced or serious collector1 and some of them list excellent collecting localities4 ,a minimum of technical terminology has been used1 but terms not commonly found in dictionaries1 or which have not been explained in the text1 are defined in the glossary 7pp4 #aaa-aad74 ,many people have helped in the planning1 preparation1 and completion of ,texas ,fossils1 and their help is gratefully acknowledged3 ,dr4 ,keith ,young1 ,the ,university of ,texas2 ,dr4 ,harold ,beaver1 ,baylor ,university2 and ,professor ,jack ,boon1 ,arlington ,state ,college1 offered helpful suggestions and information on ,cretaceous fossils2 ,professors ,richmond ,l4 ,bronaugh1 ,baylor ,university1 and ,jack ,t4 ,hughes1 ,west ,texas ,state ,college1 provided information on vertebrate collecting localities2 ,professor ,fred ,smith1 ,texas ,a,m ,college1 supplied data on ,tertiary collecting localities and fossils which were used in illustrations2 ,dr4 ,saul ,aronow and ,professor ,darrell ,davis1 ,lamar ,state ,college of ,technology2 ,dr4 ,jules ,du,bar1 ,university of ,houston2 and ,dr4 ,samuel ,p4 ,ellison1 ,the ,university of ,texas1 made valuable suggestions which have been incorporated into the manuscript4 ,special thanks are due ,drs4 ,john ,t4 ,lonsdale1 ,l4 ,f4 ,brown1 ,jr41 and ,peter ,u4 ,rodda1 ,bureau of ,economic ,geology1 who critically read the manuscript and contributed greatly to the presentation of the material2 ,dr4 ,john ,a4 ,wilson1 ,the ,university of ,texas1 who read the section on vertebrate fossils and made invaluable suggestions and criticisms2 ,miss ,josephine ,casey1 who edited the manuscript2 and ,mr4 ,j4 ,w4 ,macon1 who prepared the maps and charts4 ,thanks are due also to ,dr4 ,g4 ,a4 ,cooper1 ,united ,states ,national ,museum1 who prepared ,plate #c especially for this publication1 and to ,r4 ,t4 ,bird and the ,american ,museum of ,natural ,history for photographs used in ,plates #d and #dc4 ,plates #ch and #ci were provided through the courtesy of ,dr4 ,j4 ,w4 ,dixon1 ,jr41 and the ,geology ,department of ,baylor ,university4 ,the other photographs were prepared by the writer4 ,to ,sarah ,louise ,wilson1 ,lamar ,state ,college of ,technology1 the writer gratefully acknowledges her tireless and painstaking efforts in preparing the many fine drawings which make up the balance of the illustrations4 ,,what ,,are ,,fossils8 ,fossils are the remains or evidence of ancient plants or animals that have been preserved in the rocks of the earth's crust4 ,most fossils represent the preservable hard parts of some prehistoric organism that once lived in the area in which the remains were collected4 ,the word fossil is derived from the ,latin word fossilis1 meaning 8dug up10 and for many years any unusual object dug out of the ground was considered to be a 8fossil40 ,for this reason some of the earlier books dealing with fossils include discussions of rocks1 minerals1 and other inorganic objects4 ,there is much evidence to indicate that man has been interested in fossils since the very earliest times1 and fossil shells1 bones1 and teeth have been found associated with the remains of primitive and prehistoric men4 ,it is quite possible that the owners of these objects believed that they possessed supernatural powers1 such as healing properties or the ability to remove curses4 ,during the earliest periods of recorded history1 certain ,greek scholars found the remains of fish and sea shells in desert and mountainous regions4 ,these men were greatly puzzled by the occurrence of these objects at such great distances from the sea1 and some of them devoted considerable time to an explanation of their presence4 ,in #dej ,b4,c41 ,herodotus noticed fossils in the ,egyptian desert and correctly concluded that the ,mediterranean ,sea had once been in that area4 ,aristotle in #djj ,b4,c4 stated that fossils were organic in origin but that they were embedded in the rocks as a result of mysterious plastic forces at work within the earth4 ,one of his students1 ,theophrastus 7about #cej ,b4,c471 also believed that fossils represented some form of life but thought that they had developed from seeds or eggs that had been planted in the rocks4 ,strabo 7about #fc ,b4,c4 to ,a4,d4 #bj7 was another important ,greek scholar who attempted to explain the presence of fossils4 ,he noted the occurrence of marine fossils well above sea level and correctly inferred that the rocks containing them had been subjected to considerable elevation4 ,during the 8,dark ,ages0 fossils were alternately explained as freaks of nature1 the remains of attempts at special creation1 and devices of the devil which had been placed in the rocks to lead men astray4 ,these superstitious beliefs and the opposition from religious authorities hindered the study of fossils for hundreds of years4 ,in approximately the middle of the fifteenth century the true origin of fossils was generally accepted1 and they were considered to be the remains of prehistoric organisms which had been preserved in the earth's crust4 ,with the definite recognition of fossils as organic remains1 many of the more primitive theories were discarded for one just as impractical--these remains were considered remnants of the ,great ,flood as recorded in the ,scriptures4 ,the resulting controversy between scientists and theologians lasted for about #cjj years4 ,during the ,renaissance several of the early natural scientists concerned themselves with investigations of fossils4 ,noteworthy among these was ,leonardo da ,vinci1 the famous ,italian artist1 naturalist1 and engineer4 ,leonardo insisted that the ,flood could not be responsible for all fossils nor for their occurrence in the highest mountains4 ,he reaffirmed the belief that fossils were indisputable evidence of ancient life1 and that the sea had once covered northern ,italy4 ,leonardo explained that the remains of the animals that had inhabited this ancient body of water were buried in the sediments of the sea floor1 and that at some later date in earth history this ocean bottom was elevated well above sea level to form the ,italian peninsula4 ,in the late eighteenth and early nineteenth centuries the study of fossils became firmly established as a science1 and since that time fossils have become increasingly important to the geologist4 ,,the ,,study ,,of ,,fossils ,the study of fossils is called paleontology 7,greek palaios1 ancient2 ontos1 a being2 logos1 word or discourse74 ,information gathered with the help of paleontology has greatly increased the knowledge of ancient plants and animals and of the world in which they lived4 ,fossils represent the remains of such great numbers and various types of organisms that paleontologists have found it helpful to establish four main divisions within their science4 ,paleobotany ,paleobotany deals with the study of fossil plants and the record of the changes which they have undergone4 ,invertebrate ,paleontology ,this is the study of fossil animals without a backbone or spinal column4 ,these include such forms as fossil protozoans 7tiny one-celled animals71 snails1 clams1 starfish1 and worms1 and usually represent the remains of animals that lived in prehistoric seas4 ,because invertebrate remains are the most common fossils in ,texas1 this book is devoted largely to the discussion of invertebrate fossils and their method of collection4 ,vertebrate ,paleontology ,the vertebrate paleontologist studies the fossils of animals which possessed a backbone or spinal column4 ,the remains of fish1 amphibians1 reptiles1 birds1 and mammals are typical vertebrate fossils4 ,micropaleontology ,micropaleontology is the study of fossils that are so small that they are best studied under a microscope4 ,these tiny remains are called microfossils and usually represent the shells or fragments of minute plants or animals4 ,because of their small size1 microfossils can be brought out of wells without being damaged by the mechanics of drilling or coring4 ,for this reason microfossils are particularly valuable to the petroleum geologist who uses them to identify rock formations thousands of feet below the surface4 ,,preservation ,,of ,,fossils ,the majority of fossils are found in marine sedimentary rocks4 ,these are rocks that were formed when salt-water sediments1 such as limy muds1 sands1 or shell beds1 were compressed and cemented together to form rocks4 ,only rarely do fossils occur in igneous and metamorphic rocks4 ,the igneous rocks were once hot and molten and had no life in them1 and metamorphic rocks have been so greatly changed or distorted that any fossils that were present in the original rock have usually been destroyed or so altered as to be of little use to the paleontologist4 ,but even in the sedimentary rocks only a minute fraction of prehistoric plants and animals have left any record of their existence4 ,this is not difficult to understand in view of the rather rigorous requirements of fossilization4 ,,requirements ,,of ,,fossilization ,although a large number of factors ultimately determine whether an organism will be fossilized1 the three basic requirements are3 #a4 ,the organism should possess hard parts4 ,these might be shell1 bone1 teeth1 or the woody tissue of plants4 ,however1 under very favorable conditions of preservation it is possible for even such fragile material as an insect or a jellyfish to become fossilized4 #b4 ,the organic remains must escape immediate destruction after death4 ,if the body parts of an organism are crushed1 decayed1 or badly weathered1 this may result in the alteration or complete destruction of the fossil record of that particular organism4 #c4 ,rapid burial in a material capable of retarding decomposition4 ,the type of material burying the remains usually depends upon where the organism lived4 ,the remains of marine animals are common as fossils because they fall to the sea floor after death1 and here they are covered by soft muds which will be the shales and limestones of later geologic periods4 ,the finer sediments are less likely to damage the remains1 and certain fine-grained ,jurassic limestones in ,germany have faithfully preserved such delicate specimens as birds1 insects1 and jellyfishes4 ,ash falling from nearby volcanoes has been known to cover entire forests1 and some of these fossil forests have been found with the trees still standing and in an excellent state of preservation4 ,quicksand and tar are also commonly responsible for the rapid burial of animals4 ,the tar acts as a trap to capture the beasts and as an antiseptic to retard the decomposition of their hard parts4 ,the ,rancho ,la ,brea tar pit at ,los ,angeles1 ,california1 is famous for the large number of fossil bones that have been recovered from it4 ,these include such forms as the sabre-tooth cat1 giant ground sloths1 and other creatures that are now extinct4 ,the remains of certain animals that lived during the ,ice ,ages have been incorporated into the ice or frozen ground1 and some of these frozen remains are famous for their remarkable degree of preservation4 ,,missing ,,pages ,,in ,,the ,,record ,although untold numbers of organisms have lived on the earth in past ages1 only a minute fraction of these have left any record of their existence4 ,even if the basic requirements of fossilization have been fulfilled1 there are still other reasons why some fossils may never be found4 ,for example1 large numbers of fossils have been destroyed by erosion or their hard parts have been dissolved by underground waters4 ,others were entombed in rocks that were later subjected to great physical change1 and fossils enclosed in these rocks are usually so damaged as to be unrecognizable4 ,then1 too1 many fossiliferous rocks cannot be studied because they are covered by water or great thicknesses of sediments1 and still others are situated in places that are geographically inaccessible4 ,these and many other problems confront the paleontologist as he attempts to catalog the plants and animals of the past4 ,the missing pages in the fossil record become more obvious and more numerous in the older rocks of the earth's crust4 ,this is because the more ancient rocks have had more time to be subjected to physical and chemical change or to be removed by erosion4 ,,different ,,kinds ,,of ,,fossil ,,preservation ,there are many different ways in which plants and animals may become fossilized4 ,the method of preservation is usually dependent upon 7#a7 the original composition of the organism1 7#b7 where it lived1 and 7#c7 the forces that affected it after death4 ,most paleontologists recognize four major types of preservation1 each being based upon the composition of the remains or the changes which they have undergone4 ,,original ,,soft ,,parts ,,of ,,organisms ,this type of fossil is formed only under very special conditions of preservation4 ,to be preserved in this manner1 the organism must be buried in a medium capable of retarding decomposition of the soft parts4 ,materials that have been known to produce this type of fossilization are frozen soil or ice1 oil-saturated soils1 and amber 7fossil resin74 ,it is also possible for organic remains to become so desiccated that a natural mummy is formed4 ,this usually occurs only in arid or desert regions and when the remains have been protected from predators and scavengers4 ,probably the best-known examples of preserved soft parts of fossil animals have been discovered in ,alaska and ,siberia4 ,the frozen tundra of these areas has yielded the remains of large numbers of frozen mammoths--a type of extinct elephant 7,pl4 #di74 ,many of these huge beasts have been buried for as long as #be1jjj years1 and their bodies are exposed as the frozen earth begins to thaw4 ,some of these giant carcasses have been so well preserved that their flesh has been eaten by dogs and their tusks sold by ivory traders4 ,many museums display the original hair and skin of these elephants1 and some have parts of the flesh and muscle preserved in alcohol4 ,original soft parts have also been recovered from oil-saturated soils in eastern ,poland4 ,these deposits yielded the well-preserved nose-horn1 a foreleg1 and part of the skin of an extinct rhinoceros4 ,the natural mummies of ground sloths have been found in caves and volcanic craters in ,new ,mexico and ,arizona4 ,the extremely dry desert atmosphere permitted thorough dehydration of the soft parts before decay set in1 and specimens with portions of the original skin1 hair1 tendons1 and claws have been discovered4 ,one of the more interesting and unusual types of fossilization is preservation in amber4 ,this type of preservation was made possible when ancient insects were trapped in the sticky gum that exuded from certain coniferous trees4 ,with the passing of time this resin hardened1 leaving the insect encased in a tomb of amber1 and some insects and spiders have been so well preserved that even fine hairs and muscle tissues may be studied under the microscope4 ,although the preservation of original soft parts has produced some interesting and spectacular fossils1 this type of fossilization is relatively rare1 and the paleontologist must usually work with remains that have been preserved in stone4 ,,original ,,hard ,,parts ,,of ,,organisms ,almost all plants and animals possess some type of hard parts which are capable of becoming fossilized4 ,such hard parts may consist of the shell material of clams1 oysters1 or snails1 the teeth or bones of vertebrates1 the exoskeletons of crabs1 or the woody tissue of plants4 ,these hard parts are composed of various minerals which are capable of resisting weathering and chemical action1 and fossils of this sort are relatively common4 ,many of the fossil mollusks found in the ,tertiary and ,cretaceous rocks of ,texas have been preserved in this manner4 ,in some of the specimens the original shell material is so well preserved that the iridescent mother-of-pearl layer of the shell is found virtually intact4 ,this type of preservation is less common1 however1 in the older rocks of the ,state4 ,illustration3 ,,plate #b ,types of ,fossil ,preservation ,figures-- #a4 ,internal mold of a ,texas ,cretaceous ammonite 774 #b4 ,internal and external molds of gastropods and pelecypods in ,cedar ,park limestone member of the ,walnut clay of ,comanchean age 774 ,specimen from quarry near ,cedar ,park1 ,williamson ,county1 ,texas4 #c4 ,internal mold of a ,texas ,cretaceous pelecypod 774 #d4 ,fossil worm tubes on mold of a ,cretaceous ammonite 774 #e4 ,petrified or permineralized mammal bone of ,tertiary age 774 #f4 ,internal mold 7steinkern7 of a typical ,texas ,cretaceous gastropod 774 #g4 ,carbon residue of a ,tertiary fish 774 ,at certain localities in north and central ,texas the ,woodbine sands of ,upper ,cretaceous age 7geologic time scale and geologic map1 ,pls4 #a1 #aj7 contain large numbers of shark and fish teeth 7,pl4 #cg71 fish scales and vertebrae4 ,the remains of these vertebrates are unusually well preserved and are prized by both amateur and professional collectors4 ,calcareous ,remains ,hard parts composed of calcite 7calcium carbonate7 are very common among the invertebrates4 ,this is particularly true of the shells of clams1 snails1 and corals4 ,many of these shells have been preserved with little or no evidence of physical change 7,pl4 #b74 ,phosphatic ,remains ,the bones and teeth of vertebrates and the exoskeletons of many invertebrates contain large amounts of calcium phosphate4 ,because this compound is particularly weather resistant1 many phosphatic remains 7such as the fish teeth in the ,woodbine sands7 are found in an excellent state of preservation4 ,siliceous ,remains ,many organisms having skeletal elements composed of silica 7silicon dioxide7 have been preserved with little observable change4 ,the siliceous hard parts of many microfossils and certain types of sponges have become fossilized in this manner 7,pl4 #ad74 ,chitinous ,remains ,some organisms have an exoskeleton 7outer body covering7 composed of chitin1 a material that is similar to finger nails4 ,the fossilized chitinous exoskeletons of arthropods and other organisms are commonly preserved as thin films of carbon because of their chemical composition and method of burial4 ,,altered ,,hard ,,parts ,,of ,,organisms ,the original hard parts of an organism normally undergo great change after burial4 ,these changes take place in many ways1 but the type of alteration is usually determined by the composition of the hard parts and where the organism lived4 ,some of the more common processes of alteration are discussed below4 ,carbonization ,this process1 known also as distillation takes place as organic matter slowly decays after burial4 ,during the process of decomposition1 the organic matter gradually loses its gases and liquids leaving only a thin film of carbonaceous material 7,pl4 #b1 fig4 #g74 ,this is the same process by which coal is formed1 and large numbers of carbonized plant fossils have been found in many coal deposits4 ,in ,texas the carbonized remains of plants1 fish1 and certain invertebrates have been preserved in this manner1 and some of these carbon residues have accurately recorded even the most minute structures of these organisms4 ,petrifaction or ,permineralization ,many fossils have been permineralized or petrified--literally turned to stone4 ,this type of preservation occurs when mineral-bearing ground waters infiltrate porous bone1 shell1 or plant material4 ,these underground waters deposit their mineral content in the empty spaces of the hard parts making them heavier and more resistant to weathering4 ,some of the more common minerals deposited in this manner are calcite1 silica1 and various compounds of iron4 ,replacement or ,mineralization ,this type of preservation takes place when the original hard parts of organisms are removed after being dissolved by underground water4 ,this is accompanied by almost simultaneous deposition of other substances in the resulting voids4 ,some replaced fossils will have the original structure destroyed by the replacing minerals4 ,others1 as in the case of certain silicified tree trunks1 may be preserved in minute detail4 ,although more than #ej minerals have been known to replace original organic structures1 the most frequent replacing substances are calcite1 dolomite 7a calcium magnesium carbonate71 silica1 and certain iron compounds4 ,replacement by calcareous material ,calcareous replacement occurs when the hard parts of an organism are replaced by calcite1 dolomite1 or aragonite 7a mineral which is composed of calcium carbonate but which is less stable than calcite74 ,the exoskeletons of many corals1 echinoderms1 brachiopods1 and mollusks have been replaced in this manner4 ,replacement by siliceous material ,when the original organic hard parts have been replaced by silica the fossil is said to have undergone silicification1 and this type of replacement often produces a very high degree of preservation4 ,this is particularly true of the silicified ,permian 7geologic time scale1 ,pl4 #a7 fossils from the ,glass ,mountains in ,brewster ,county4 ,these fossils are embedded in limestone which must be dissolved in vats of acid1 and after the enclosing rock has been dissolved the residue yields an amazing variety of perfectly preserved invertebrate fossils 7,pl4 #c74 ,silicified ,cretaceous fossils have been recovered from the ,edwards limestone of central ,texas4 ,the silicified fauna is restricted to a few scattered localities1 each of which may yield many unusually well-preserved fossils4 ,replacement by iron compounds ,several different iron compounds have been known to replace organic matter4 ,many ,texas limestones contain fossil snails and clams which have had their original shell material replaced by iron compounds such as limonite1 hematite1 marcasite1 or pyrite4 ,certain of the fossiliferous ,tertiary sandstones of the ,texas ,gulf ,coast area contain large amounts of glauconite which commonly replaced organic material4 ,in some areas entire faunas have been replaced by iron compounds4 ,such is the case in the famous 8,pyrite ,fossil ,zone0 of the ,pawpaw formation 7,lower ,cretaceous7 in ,tarrant ,county4 ,the fossils in this part of the formation are very small or 8dwarfed0 and have been replaced by limonite1 hematite1 or pyrite4 ,ammonites1 clams1 snails1 and corals are particularly abundant at this locality4 ,,traces ,,of ,,organisms ,fossils consist not only of plant and animal remains but of any evidence of their existence4 ,in this type of fossilization there is no direct evidence of the original organism1 rather there is some definite indication of the former presence of some ancient plant or animal4 ,objects of this sort normally furnish considerable information as to the identity or characteristics of the organism responsible for them4 ,molds and ,casts ,many shells1 bones1 leaves1 and other forms of organic matter are preserved as molds and casts4 ,if a shell had been pressed down into the ocean bottom before the sediment had hardened into rock1 it may have left the impression of the exterior of the shell4 ,this impression is known as a mold 7,pl4 #b74 ,if at some later time this mold was filled with another material1 this produced a cast4 ,this cast will show the original external characteristics of the shell4 ,such objects are called external molds if they show the external features of the hard parts 7,pl4 #b1 fig4 #b7 and internal molds 7,pl4 #b1 fig4 #c7 if the nature of the inner parts is shown4 ,molds and casts are to be found in almost all of the fossil-bearing rocks of ,texas1 and they make up a large part of most fossil collections4 ,it is particularly common to find fossil clams and snails preserved by this method4 ,this is primarily because their shells are composed of minerals that are relatively easy to dissolve1 and the original shell material is often destroyed4 ,illustration3 ,,plate #c ,silicified ,brachiopods ,all specimens from ,permian limestones of the ,glass ,mountains1 ,brewster ,county1 ,texas ,figures-- #a1 #b4 ,avonia sp41 #b4 ,ventral and side view of two pedicle valves showing long slender spines4 #c4 ,avonia sp41 #f4 ,young specimen showing attachment ring at apex4 #d-f4 ,muirwoodia multistriatus ,meek1 #d4 ,respectively1 side and ventral view of pedicle valve and dorsal view of brachial valve4 #g-i4 8,marginifera0 opima ,girty4 ,respectively1 ventral and side view of pedicle valve showing long stout spines 7#d7 and interior of brachial valve showing muscle scars and brachial ridges 7#b74 #aj-ac4 ,aulosteges tuberculatus ,r4 ,e4 ,king1 #d4 ,respectively1 side and interior view of brachial valve showing muscle scars2 ventral view of pedicle valve showing brush of attachment spines on ears2 and ventral view of a young pedicle valve4 #ad4 ,avonia sp41 #d4 ,ventral view of a specimen with long spines4 #ae1 #af4 ,avonia subhorrida 7,meek71 #b4 ,ventral view of a pedicle valve and dorsal view of a brachial valve showing spines on both4 #ag4 ,avonia signata 7,girty71 #b4 ,dorsal view of a large specimen showing hairlike spines on brachial valve4 #ah-bj4 ,prorichthofenia permiana 7,shumard74 ,respectively1 side and posterior view of pedicle valve 7#d7 and interior of dorsal valve 7#b7 showing anchor spines and interior spines of the brachial valve4 #ba4 ,heteralosia hystricula 7,girty71 #b4 ,cluster of individuals attached to a large ,marginifera4 ,photograph courtesy of ,dr4 ,g4 ,a4 ,cooper1 ,u4 ,s4 ,national ,museum4 ,tracks1 ,trails1 and ,burrows ,many animals have left records of their movements over dry land or the sea bottom4 ,some of these1 such as footprints 7,pl4 #d71 indicate not only the type of animal that left them but often provide valuable information about the animal's environment4 ,thus1 the study of a series of dinosaur tracks would not only indicate the size and shape of the foot but also provide some information as to the weight and length of the animal4 ,in addition1 the type of rock containing the track would help determine the conditions under which the dinosaur lived4 ,some of the world's most famous dinosaur tracks are to be found in the ,lower ,cretaceous limestones in ,somervell ,county1 ,texas4 ,these footprints1 which are about #aaj1jjj1jjj years old 7,pl4 #d71 were discovered in the bed of ,paluxy ,creek near the town of ,glen ,rose4 ,large segments of the rock containing these tracks were collected by paleontologists of the ,american ,museum of ,natural ,history in ,new ,york ,city and the ,texas ,memorial ,museum at ,austin4 ,great slabs of limestone were transported to the museums1 replaced in their original position1 and are now on display as mute evidence of the gigantic size of these tremendous reptiles4 ,invertebrates also leave tracks and trails of their activities1 and these markings may be seen on the surfaces of many sandstone and limestone deposits4 ,these may be simple tracks1 left as the animal moved over the surface1 or the burrows of crabs or other burrowing animals4 ,markings of this sort provide some evidence of the manner of locomotion of these organisms and of the type of environment that they inhabited4 ,coprolites ,coprolites are fossil dung or body waste 7fig4 #a74 ,these objects can provide valuable information as to the food habits or anatomical structure of the animal that made them4 ,illustration3 ,fig4 #a4 ,sketch of a coprolite--fossilized animal excrement4 ,gastroliths ,these highly polished well-rounded stones 7fig4 #b7 are believed to have been used in the stomachs of reptiles for grinding the food into smaller pieces4 ,large numbers of these 8stomach stones0 have been found with the remains of certain types of dinosaurs4 ,illustration3 ,fig4 #b4 ,sketch of a gastrolith--the gizzard stone of an ancient reptile4 ,,pseudofossils ,among the many inorganic objects formed by nature there are some that bear superficial resemblance to plants or animals4 ,because they are often mistaken for organic remains1 these objects have been called pseudofossils1 or 8false fossils40 ,dendrites ,illustration3 ,fig4 #c4 ,dendrites4 ,these thin branching mineral deposits bear a marked resemblance to plants1 hence they are called pseudofossils4 ,although these closely resemble the remains of ferns or other plant material 7fig4 #c71 dendrites are actually thin incrustations of manganese dioxide4 ,they are often found along the bedding planes of ,cretaceous and ,paleozoic 7geologic time scale1 ,pl4 #a7 limestones in many parts of ,texas4 ,illustration3 ,plate #d ,dinosaur tracks in limestone in bed of ,paluxy ,creek near ,glen ,rose1 ,somervell ,county1 ,texas4 ,photograph courtesy of the ,american ,museum of ,natural ,history4 ,permission to reproduce by ,r4 ,t4 ,bird4 ,slickensides ,these are striations that are produced when rock surfaces move past each other while being fractured4 ,slickensides may superficially resemble certain of the ,pennsylvanian coal plants of ,texas4 ,since slickensides are commonly at an angle to the bedding plane and plant remains lie parallel to the bedding plane1 the two are usually easily distinguished4 ,concretions ,many shales and sandstones contain hardened masses of minerals and rock that are often mistaken for fossils4 ,these masses1 called concretions1 are usually found weathered out of the surrounding rock and may assume the shape of bones1 flowers1 vegetables1 turtles1 etc4 ,although these concretions do not represent organic remains1 it is sometimes possible to find true fossils inside them4 ,,where ,,and ,,how ,,to ,,collect ,,fossils ,in fossil collecting1 as in most 8collecting0 hobbies1 the key to success lies in knowing where to look1 what equipment to use1 and the most effective methods of collecting4 ,,collecting ,,equipment ,fossil collecting is a relatively inexpensive hobby because it requires a minimum of supplies and equipment4 ,however1 as in almost any hobby1 there are certain basic items of equipment that must be acquired4 ,hammer ,the hammer is the basic tool in the collector's kit4 ,almost any type of hammer is satisfactory1 but as collecting experience is gained it may be desirable to get a geologist's hammer4 ,these hammers1 also called mineralogist's or prospector's picks1 are of two types4 ,one type has a square head on one end and a pick on the other 7,pl4 #e73 the other type is similar to a stonemason's or bricklayer's hammer and has a chisel end instead of the pointed pick end4 ,the square head of the hammer is useful in breaking or chipping harder rocks1 and the chisel or pick end is good for digging1 prying1 and splitting soft rocks4 ,collecting ,bag ,it will be necessary to have some type of bag in which to carry equipment1 fossils1 and other supplies4 ,a ,boy ,scout knapsack1 musette bag 7,pl4 #e71 hunting bag1 or similar canvas or leather bag is suitable4 ,chisels ,a pair of chisels is useful when fossils must be chipped out of the surrounding rock4 ,two sizes1 preferably and #a inch1 will usually suffice4 ,a small sharp punch or awl is effective in removing smaller specimens from the softer rocks4 ,wrapping ,materials ,some specimens are more fragile than others1 and these should be handled with special care4 ,several sheets of newspaper should always be kept in the collecting bag1 and each specimen should be wrapped individually as it is collected4 ,such precautions taken in the field will usually prevent prized specimens from being broken or otherwise damaged4 ,in addition to newspaper1 it is wise to carry a supply of tissue paper in which to wrap more fragile specimens4 ,map1 ,notebook1 and ,pencil ,it is most important to have some method of recording where the fossils were found4 ,it is very easy to forget where the material was collected1 and one should never rely on memory4 ,a small pocket-sized notebook is inexpensive and just the right size to carry in the field4 ,a highway or county map should be used to find the geographic location of each collecting locality4 ,maps of ,texas counties can be obtained from the ,texas ,highway ,department1 ,file ,d-#aj1 ,austin #ad1 ,texas4 ,these maps come in three different sizes1 but for most purposes the #ahbe-;inch sheets1 with a scale of inch #a mile1 will be satisfactory4 ,these are available for all counties and may be purchased at a nominal price4 ,magnifying ,glass ,a magnifying glass or hand lens 7,pl4 #e7 is useful for looking at small specimens and will also prove helpful in examining the finer details of larger fossils4 ,a #aj-power magnification is satisfactory for most purposes1 and several inexpensive models are available4 ,paper or ,cloth ,bags ,small bags are useful in separating specimens from different localities4 ,heavy-duty hardware bags for large rough material and medium-weight grocery bags for smaller specimens may be used4 ,locality data may be written directly on the bag or on a label placed inside with the fossils4 ,as an added precaution some collectors do both4 ,the more serious collector may want to use a cloth geological sample bag 7,pl4 #e74 ,illustration3 ,plate #e ,,fossil ,,collecting ,,equipment ,,geologic ,,hammer 7,chisel end7 ,,magnifying ,,glass ,,geologic ,,hammer 7,pick end7 ,,collecting ,,bag ,,sample ,,sack ,other ,useful ,items ,the items described above are those that are most needed and constitute the basic equipment of the fossil hunter4 ,the serious amateur may wish to include certain additional items which will place his collecting on a more professional basis4 ,some of these accessory items are3 #a4 ,a topographic map of the collecting area4 ,these are available for many parts of the ,state and are published and distributed at nominal cost by the ,united ,states ,geological ,survey1 ,washington1 ,d4 ,c41 and_/or ,denver1 ,colorado4 ,the ,survey can supply an index sheet showing all such maps available for ,texas4 #b4 ,a geologic map of the collecting area if one is available4 ,the list of publications of the ,bureau of ,economic ,geology should be consulted to see if a geologic report or map of the area has been published4 ,this list may be obtained without charge from the ,bureau of ,economic ,geology1 ,the ,university of ,texas1 ,austin #ab1 ,texas4 #c4 ,the geologic map of ,texas4 ,although a geologic map of ,texas is included in this publication 7,pl4 #aj71 the scale is so small that its use is somewhat limited4 ,for more detailed work a larger geologic map in color 7scale3 #a inch #ca4ef miles7 may be ordered from the ,bureau4 ,the sale price is #be cents4 #d4 ,a compass for more accurate location of collecting localities4 #e4 ,adhesive or masking tape4 ,the locality information can be written on the tape and applied directly to the specimen4 #f4 ,paper labels 7about #ce inches74 ,a properly completed label should be placed inside each bag of material4 ,,where ,,to ,,look ,knowing where to look for fossils is a very important part of fossil collecting4 ,it has already been pointed out that igneous and metamorphic rocks are not likely to be fossiliferous1 but that most fossils are found in marine sedimentary rocks4 ,these sediments were deposited under conditions that were favorable for organisms during life and which facilitated preservation after death4 ,limestones1 limy shales1 and certain types of sandstones are typically deposited under such conditions4 ,one should look particularly for areas where rocks formed from marine sediments lie relatively flat and have not been greatly disturbed by heat1 pressure1 and other physical or chemical changes4 ,if the rocks appear to have undergone considerable folding and fracturing1 there is great likelihood that any fossils that were present have been destroyed or damaged by this action4 ,quarries are good places to look but one should be sure to obtain permission before entering4 ,rock exposures in quarries are rather fresh but have undergone some weathering4 ,quarries have been opened in many of the limestone formations of ,texas1 and large numbers of fine specimens have been collected in some of these excavations4 ,certain ,lower ,cretaceous limestones are useful for road metal1 building stone1 or in the manufacture of portland cement1 and extensive quarrying has been undertaken in the ,edwards ,plateau region of ,texas 7,pl4 #i74 ,bones and petrified wood are frequently found in sand and gravel quarries in many parts of the ,state4 ,particular attention should be given to all railroad and highway cuts as rocks exposed in this way are usually still in their original position and are fairly well weathered4 ,cuts made by recent construction are usually more productive after they have undergone a period of weathering as this helps to separate the fossils from their enclosing rocks4 ,gullies1 canyons1 and stream beds are also good places to examine4 ,these areas are continually subjected to the processes of erosion or stream action1 and new material is uncovered year after year4 ,if there are abandoned coal mines nearby1 the dumps of waste rock around the mine shafts could be checked4 ,a careful examination of such waste may reveal fine specimens of well-preserved plant fossils4 ,coal has been mined in several parts of ,texas1 and abandoned shafts or dumps are still present in some counties4 ,the bituminous coals of ,texas are predominantly ,pennsylvanian in age1 and mining has been carried on in the following counties3 ,eastland1 ,erath1 ,jack1 ,palo ,pinto1 ,parker1 ,wise1 ,young4 ,,how ,,to ,,collect ,when a likely collecting spot has been located1 the ground should be examined very carefully to see if there are any rock fragments which contain pieces of shell or the imprints of leaves or other organisms4 ,if the fossils have been freed by weathering1 they can be easily picked up and placed in the bag4 ,many times1 however1 it will be necessary to take the hammer and very carefully remove the surrounding rock4 ,smaller specimens may be more safely freed with the careful use of the proper size chisel by gently tapping the chisel and gradually chipping away the matrix--the rock that is holding the specimen4 ,after most of the matrix has been removed1 the fossil should be carefully wrapped and placed in the collecting bag4 ,before leaving a collecting locality1 one should be sure to record its geographic location and the geologic age of the rock in which the fossils were found4 ,the place should be located on the map and the locality entered in the notebook in such a manner that it could easily be located again for additional collecting4 ,if a county or topographic map is available1 it is wise to mark the locality on the map4 ,the geographic and geologic data should be written on a label placed in the bag of fossils collected at that particular locality4 ,in addition1 many collectors find it helpful to write the locality on the outside of each bag of fossils4 ,material from separate localities should be kept in individual cloth or paper bags1 and the collector should take every precaution to keep the labels with their respective fossils4 ,remember that a fossil without a locality is hardly worth the paper it is wrapped in4 ,the collector should always ask the land owner's permission before entering or collecting on private property4 ,one should respect all property1 especially livestock and fences1 and leave the area cleaner than when entered4 ,if these precautions are observed1 future collectors will probably be welcome to return for additional collecting4 ,,cleaning ,,and ,,preparation ,,of ,,fossils ,it is usually necessary to do the final cleaning and preparation of fossils at home or in the laboratory1 for most fossils brought in from the field require considerable preparation before they are ready for display4 ,excess matrix should be carefully removed with hammer and chisel2 blows should always be directed away from the fossil4 ,smaller tools 7needles1 tweezers1 and awls7 should be used in the final preparation stage1 and one should work carefully to avoid damaging the specimen4 ,before starting the final cleaning1 it will be helpful to place the fossils in water and let them soak overnight4 ,this will loosen much of the excess rock1 and most of the softer material can then be removed with a small scrub brush or tooth brush4 ,mounted needles can be used to clean more delicate specimens or around the smaller structures of larger fossils4 ,it may be advisable to use the magnifying glass when working with small fossils or with delicate surface structures of larger specimens4 ,broken fossils can be repaired with clear plastic household cement1 and specimens that are crumbling may be coated with pure white shellac1 thinned collodion1 or clear nail polish4 ,the latter is preferred as it is not as likely to crack4 ,fragments of bone are particularly apt to crumble upon exposure to the air4 ,this type of fossil is normally quite fragile and should be excavated with great care and shellaced as soon as dry4 ,dilute hydrochloric acid may be used in removing silicified fossils from a calcareous matrix4 ,the material to be etched should be placed in a pottery or glass container and covered with water4 ,acid should then be added to the water very slowly and until large numbers of bubbles are given off4 ,each time the bubbling ceases1 more acid should be added and this process should be repeated until the fossil is free of matrix4 ,this procedure should be carried on in a well-ventilated place1 and the acid should be handled with extreme caution4 ,hydrochloric acid can cause damage or serious injury and the fumes are extremely corrosive4 ,,how ,,fossils ,,are ,,named ,in order to get the maximum pleasure out of fossil collecting1 most amateur paleontologists want to identify and classify the fossils that they have collected4 ,this requires some knowledge of how fossils are classified and how they receive their scientific names4 ,,the ,,science ,,of ,,classification ,the number of organisms1 both living and extinct1 is so great that some system of classification is needed to link them all together4 ,many fossils bear distinct similarities to plants and animals that are living today1 and for this reason paleontological classification is similar to that used to classify modern organisms4 ,this system1 known as the system of binomial nomenclature1 was first used consistently in #ageh by ,linn 7or ,linnaeus71 an early ,swedish naturalist4 ,scientific names established in accordance with the principles of binomial nomenclature consist of two parts3 the generic 7or genus7 name and the trivial name4 ,these names are commonly derived from ,greek or ,latin words which are usually descriptive of the organism or fossil being named4 ,they may1 however1 be derived from the names of people or places1 and in such instances the names are always ,latinized4 ,greek or ,latin is used because they are 8dead0 languages and not subject to change4 ,they are also 8international0 languages in that scientists all over the world can use the same names regardless of what language they write in4 ,the system of binomial nomenclature has led to the development of the science of taxonomy1 the systematic classification and naming of plants and animals according to their relationships4 ,,the ,,units ,,of ,,classification ,the world of organic life has been divided into the plant and animal kingdoms4 ,these kingdoms have been further divided into larger divisions called phyla 7from the ,greek word phylon1 a race74 ,each phylum is composed of organisms with certain characteristics in common4 ,for example1 all animals with a spinal cord 7or notochord7 are assigned to the phylum ,chordata4 ,the phylum is reduced to smaller divisions called classes1 classes are divided into orders1 orders into families1 families into genera1 and each genus is divided into still smaller units called species4 ,a species may be further reduced to subspecies1 varieties1 or other subspecific categories1 but these need not concern us in a publication of this nature4 ,the following table illustrates the use of binomial nomenclature in the classification of man1 a clam1 and a dog4 ,unit ,man ,dog ,clam ,kingdom ,animalia ,animalia ,animalia ,phylum ,chordata ,chordata ,mollusca ,class ,mammalia ,mammalia ,pelecypoda ,order ,primates ,carnivora ,eulamellibranchia ,family ,hominidae ,canidae ,veneridae ,genus ,homo ,canis ,venus ,species sapiens familiaris mercenaria ,the generic name and the trivial name constitute the scientific name of a species and according to this system of classification the scientific name of all living men is ,homo sapiens4 ,it is obvious that there are many variations among individual men1 but all men have certain general characteristics in common and are therefore placed in the same species4 ,in a scientific name1 the generic name is always started with a capital letter and the trivial name with a small letter4 ,both names must be italicized or underlined4 ,the name of the author 7the person who first described the fossil7 usually appears following the scientific name4 ,the date of the scientific publication containing the original description of the fossil is often placed after the author4 ,for example3 ,turrilites worthensis ,adkins and ,winton #aibj ,with the large numbers of plants and animals that are living today1 plus those of the past1 random naming would result in much confusion4 ,for this reason scientists have established strict rules that must be followed when a specimen is named4 ,the strict application of these rules enables scientists in all parts of the world to assign scientific names without fear of duplication4 ,,identification ,,of ,,fossils ,the beginning collector is usually content to know if his specimen is a clam or a snail or a fern or a palm leaf4 ,but as the collection grows1 it becomes increasingly desirable to know the scientific name of each fossil4 ,when he starts to identify fossils it may be helpful to show them to a geology teacher if a college or university is nearby4 ,most teachers are glad to be of help and will probably have similar specimens in their own collections4 ,as all colleges do not have geology departments1 a list of institutions with geologists on their faculties is included at the end of this section of the handbook 7p4 #bg74 ,in addition1 many of the science teachers in the public schools are familiar with fossils and can give helpful suggestions as to how to classify material4 ,museums are also good places from which to get help4 ,if the museum has a geological collection1 it will be most helpful to compare specimens with the fossils in their collections and to ask the museum personnel for advice4 ,in addition to the above sources of information1 local professional geologists are usually familiar with the geology of the local area and the paleontological literature of the region4 ,possibly local librarians can recommend books1 encyclopedias1 or other publications that will be of help4 ,members of a local rock and mineral club1 if one is available1 are another source of information4 ,many times these collectors can pass along good ideas and tell exactly which books to consult4 ,after books or journals describing the fossils of the area have been located1 the collected specimens should be closely compared with any illustrations that are shown4 ,each fossil should be examined carefully1 its more characteristic features noted1 and it should again be compared with the illustrations and descriptions in the book4 ,the phylum or class to which the specimen belongs should be determined first4 ,for example1 the genus and species of a certain fossil may not be known1 but it looks like a snail and accordingly it is named a gastropod 7for class ,gastropoda1 the snail class71 and this is1 at least1 a start in determining the scientific name of that particular fossil4 ,the descriptive material in the text of each reference will usually point out the more detailed features which will be diagnostic of the genus or species4 ,the illustrations and descriptive material in this publication will also be of considerable help in identification4 ,many illustrations of the more common invertebrate fossils have been included1 but the publication was not designed primarily for use in fossil identification4 ,rather1 it is intended to guide the amateur or student who is interested in fossil collecting1 and to furnish suggestions as to how collecting may be more effectively pursued4 ,,use ,,of ,,identification ,,keys ,fossil identification keys may be useful in helping the beginning collector identify specimens4 ,the collector compares a fossil with the key description and eliminates those characters that do not fit the specimen4 ,the key used in this handbook is based primarily on symmetry--the orderly arrangement of the parts of an object with reference to lines1 planes1 or points4 ,the shape of the shell or body1 presence or absence of coiling1 and presence or absence of body partitions are also useful criteria in identifying fossils4 ,to use the key the beginner should know something about symmetry4 ,two major types of symmetry are used in this key4 #a4 ,radial symmetry--the symmetrical repetition of parts around an axis4 ,this is the symmetry of a wheel1 and any vertical section through the center of the object divides it into symmetrical halves 7fig4 #d;a74 #b4 ,bilateral symmetry--the symmetrical duplication of parts on each side of a plane 7fig4 #e74 ,the plane divides the object into two halves that are mirror images of each other4 ,this is the symmetry of a plank4 ,it should be noted that many objects may have both kinds of symmetry4 ,for example3 ,a cone when viewed from the top has radial symmetry and when viewed from the side shows bilateral symmetry 7fig4 #d;a1 b74 ,illustration3 ,fig4 #d4 ,types of symmetry in a fossil coral4 7a7 ,radial symmetry4 7b7 ,bilateral symmetry4 ,illustration3 ,fig4 #e4 ,bilateral symmetry as displayed by a typical fossil brachiopod4 ,an illustration of the use of the key on pages #bf-bg follows4 ,assuming that a specimen displays radial symmetry1 this means that it belongs under ,part ,i on the key4 ,if the fossil has a tapering1 cylindrical1 cone-shaped shell 78,a0 on the key71 the subheadings under the 8,a0 part of the key are examined4 ,should the specimen have a shell which is round1 tapering at one end1 with transverse septa or sutures 7number #b under 8,a071 it is probably a cephalopod4 ,this is indicated on the right hand side of the page4 ,number #a under 8,a0 is eliminated because the fossil did not have longitudinal radial partitions within the shell4 ,some fossils display no apparent symmetry and such a fossil would be referred to ,part ,,iii of the key4 ,if this fossil had internal transverse partitions 8,a0 would be eliminated4 ,if the fossil was not a coiled fossil 8,b0 would also be eliminated and we would proceed directly to 8,c0--uncoiled fossils4 ,if the specimen is a branching twig-like fossil1 numbers #a1 #b1 and #c would be eliminated and the specimen referred to number #d 7,branching twig-like fossils74 ,should the specimen have evenly distributed relatively large openings with radial longitudinal partitions or septa1 the specimen is probably a colonial coral 78b0 under number #d on the key74 ,the 8a0 part of number #d would be eliminated because the coral had large openings and radial longitudinal septa4 ,once a tentative identification has been made from the key1 pictures and descriptions of this fossil group are examined to establish a more precise identification4 ,it should be remembered that keys are not perfect1 and the collector should not expect to be able to identify every specimen with this key4 ,,identification ,,key ,,to ,,main ,,types ,,of ,,invertebrate ,,fossils 7,instructions on pages #bc-be for use of key7 ,i4 ,fossils displaying radial symmetry--symmetrical repetition of parts around a central axis ,a4 ,fossil tapering1 cylindrical1 cone-shaped3 #a4 ,fossil with longitudinal radial partitions or septa2 cone-shaped ,coral #b4 ,shell with transverse septa or sutures2 tapering at one end ,cephalopod #c4 ,shell without internal septa or partitions3 a4 ,shell large1 heavy2 usually with external longitudinal ribs4 ,occur only in ,cretaceous rocks ,rudistid b4 ,shell small 7usually less than #b inches long71 tusk-shaped1 open at both ends4 ,rare in ,paleozoic and ,mesozoic rocks ,scaphopod ,b4 ,fossil disk-shaped or flattened dome-shaped3 #a4 ,fossil with radiating star pattern on top ,echinoid #b4 ,fossil subconical to hemispherical1 dome-shaped2 base concave or flat2 minute pits or pores covering surface2 typically small 7less than #c inches across7 ,bryozoa #c4 ,fossil small 7less than inch72 generally disk-shaped ,foraminifera 7orbitoidid7 #d4 ,fossil disk-shaped or button-like2 with longitudinal1 radial partitions or septa ,coral ,c4 ,fossil composed of segments or plates3 #a4 ,fossil composed of circular segments1 disks1 or chambers2 when united form cylinder3 a4 ,tapered shell ,cephalopod b4 ,non-tapered1 segments small and of relatively uniform thickness with hole in center2 individual columnals disk-shaped ,crinoid stem #b4 ,fossil composed of many-sided plates3 a4 ,bud-shaped fossil of #ac wedge-shaped plates ,blastoid b4 ,cup-shaped fossil of many curved plates surrounded by branching arms ,crinoid ,,ii4 ,fossils displaying bilateral symmetry--symmetrical duplication of parts on each side of a plane ,a4 ,fossil coiled in a single plane3 #a4 ,shell divided by internal transverse partitions or sutures ,cephalopod #b4 ,shell without internal partitions or sutures ,gastropod #c4 ,shell small2 spindle-shaped2 resembles wheat grain4 ,common in ,pennsylvanian and ,permian rocks ,foraminifera 7fusulinids7 ,b4 ,fossil not coiled3 #a4 ,shells or valves similar to clams3 a4 ,plane of symmetry parallel to hinge2 equivalved ,pelecypod b4 ,plane of symmetry 7almost bilaterally symmetrical7 at right angles to hinge line2 mostly inequivalved2 strongly ribbed4 8,scallop-like0 with 8ears40 ,rare in ,paleozoic rocks ,pelecypod c4 ,plane of symmetry at right angles to hinge line2 inequivalved2 not 8scallop-like0 and without 8ears40 ,larger valve commonly has an opening in beak4 ,common in ,paleozoic rocks ,brachiopod #b4 ,fossil tapering1 cylindrical1 cone-shaped3 a4 ,fossil with internal longitudinal1 radial septa or partitions2 cone-shaped ,coral b4 ,shell with internal transverse partitions or sutures2 tapering at one end ,cephalopod c4 ,shell without internal septa or partitions4 7#a7 ,shell large1 heavy2 usually with external longitudinal ribs4 ,occur only in ,cretaceous rocks ,rudistid 7#b7 ,shell small 7usually less than #b inches71 tusk-shaped1 open at both ends4 ,rare in ,paleozoic and ,mesozoic rocks ,scaphopod #c4 ,fossil heart-shaped1 domed or flattened2 radial star pattern on top ,echinoid #d4 ,fossil segmented3 a4 ,fossil divided into #c lobes2 may be curled up4 ,not found in ,mesozoic or ,cenozoic rocks ,trilobite b4 ,fossil flattened or elongate2 resembles shrimp1 crab1 or crayfish ,crustacean ,,iii4 ,fossils displaying no apparent symmetry ,a4 ,shell without transverse internal partitions or sutures3 #a4 ,shell coiled like ram's horn1 low spired1 opening of shell very large2 surface has concentric ridges4 ,shell has two valves2 smaller1 flattened valve not often found4 ,in ,texas found only in ,cretaceous rocks ,pelecypod 7,note3 ,some ,paleozoic gastropods1 8#b10 closely resemble larger valve of these pelecypods7 #b4 ,shell tightly coiled2 most have higher spire than 8#a40 ,opening of shell smaller than 8#a02 shell not as rough as 8#a0 and has only one valve ,gastropod ,b4 ,coiled fossils2 coiling not in one plane3 #a4 ,shell with transverse internal partitions or sutures3 a4 ,partitions always smooth2 thick shelled2 loosely and irregularly coiled1 usually in large compact masses of many individual shells4 ,occur only in ,cretaceous rocks ,caprinid b4 ,partitions 7sutures7 usually wrinkled2 relatively thin shelled2 mostly regularly and tightly coiled2 occur as separate individual specimens ,cephalopod #b4 ,shell without transverse internal partitions or sutures ,gastropod #c4 ,solid spiral ridge around central axis2 resembles a corkscrew ,bryozoa ,c4 ,uncoiled fossils3 #a4 ,fossil resembles a narrow saw blade2 typically found as thin film of carbon4 ,not found in ,mesozoic or ,cenozoic rocks ,graptolite #b4 ,fossil irregularly cone-shaped2 longitudinal radial partitions or septa ,coral #c4 ,shell resembles a clam or oyster shell but valve or shell not symmetrical ,pelecypod 7mostly oysters7 #d4 ,branching twig-like fossils3 a4 ,fossils covered with minute pores or openings ,bryozoa b4 ,fossils with evenly distributed1 relatively large openings with longitudinal radial partitions or septa ,colonial coral #e4 ,lace-like fossils2 occur as thin sheets or films ,bryozoa #f4 ,fossils composed of radiating masses of polygonal or circular tubes containing radial septa ,colonial coral #g4 ,irregular fossils2 typically cylindrical with rough surface3 a4 ,fossil has large axial opening and thick wall2 usually has external longitudinal ribs4 ,occurs only in ,cretaceous rocks ,rudistid b4 ,fossil solid with no large axial opening2 surface with small pits or pores 7fewer than in ,bryozoa74 ,in ,texas1 occurs most commonly in ,pennsylvanian and ,permian rocks ,sponge ,,list ,,of ,,texas ,,colleges ,,offering ,,geology ,,courses ,a4,m4 ,college of ,texas1 ,college ,station ,amarillo ,college1 ,amarillo ,arlington ,state ,college1 ,arlington ,austin ,college1 ,sherman ,baylor ,university1 ,waco ,blinn ,college1 ,brenham ,corpus ,christi1 ,university of1 ,corpus ,christi ,del ,mar ,college1 ,corpus ,christi ,east ,texas ,state ,college1 ,commerce ,hardin-,simmons ,university1 ,abilene ,henderson ,county ,junior ,college1 ,athens ,houston1 ,university of1 ,houston ,howard ,county ,junior ,college1 ,big ,spring ,kilgore ,college1 ,kilgore ,lamar ,state ,college of ,technology1 ,beaumont ,lee ,college1 ,baytown ,mc,murry ,college1 ,abilene ,midwestern ,university1 ,wichita ,falls ,north ,texas ,state ,college1 ,denton ,odessa ,college1 ,odessa ,pan ,american ,college1 ,edinburg ,rice ,university1 ,houston ,st4 ,mary's ,university1 ,san ,antonio ,san ,angelo ,college1 ,san ,angelo ,san ,antonio ,college1 ,san ,antonio ,southern ,methodist ,university1 ,dallas ,south ,texas ,college1 ,houston ,southwestern ,university1 ,georgetown ,stephen ,f4 ,austin ,state ,college1 ,nacogdoches ,sul ,ross ,state ,college1 ,alpine ,tarleton ,state ,college1 ,stephenville ,texarkana ,college1 ,texarkana ,texas ,christian ,university1 ,fort ,worth ,texas ,college1 ,tyler ,texas ,college of ,arts and ,industries1 ,kingsville ,texas ,technological ,college1 ,lubbock ,texas ,western ,college1 ,el ,paso ,the ,university of ,texas1 ,austin ,trinity ,university1 ,san ,antonio ,tyler ,junior ,college1 ,tyler ,west ,texas ,state ,college1 ,canyon ,illustration3 ,plate #f ,fossil ,identification ,chart ,i ,,radial ,,symmetry ,a4 ,tapering1 cylindrical cone-shaped fossils #a4 ,cone-shaped with longitudinal partitions or septa ,coral #b4 ,fossils with septa or sutures2 tapering at one end ,cephalopod #c4 ,shell without internal partitions or sutures a4 ,shell large heavy1 external longitudinal ribs4 ,cretaceous only ,rudistid b4 ,shell small1 tusk-shaped open at both ends4 ,rare in ,paleozoic and ,mesozoic ,scaphopod ,b4 ,disc or dome-shaped fossils #a4 ,star pattern on top ,echinoid #b4 ,subconical small pits or pores on top ,bryozoan #c4 ,small disc-shaped 7less than inch7 ,orbitoid ,foraminifera #d4 ,disc-shaped or button-like1 with longitudinal partitions or septa ,coral ,c4 ,fossils composed of segments or plates #a4 ,circular discs or chambers2 when united form cylinder a4 ,tapered shell ,cephalopod b4 ,not tapered1 segments small of uniform thickness1 hole in center ,crinoid ,stem #b4 ,fossil composed of many-sided plates a4 ,bud-shaped1 #ac wedge-shaped plates ,blastoid b4 ,cup-shaped1 many curved plates branching arms ,crinoid ,illustration3 ,plate #g ,fossil ,identification ,chart ,,ii ,,bilateral ,,symmetry ,a4 ,fossil coiled in a single plane #a4 ,shell divided by internal transverse partitions or sutures ,cephalopod #b4 ,shell without internal partitions or sutures ,gastropod #c4 ,shell small1 spindle-shaped2 resembles wheat grain4 ,pennsylvanian and ,permian ,foraminifera fusulinid ,b4 ,fossil not coiled #a4 ,shells or valves similar to clams a4 ,plane of symmetry parallel to hinge2 equivalved ,pelecypod b4 ,plane of symmetry almost at right angles to hinge2 strongly ribbed2 8,scallop-like0 with 8ears01 inequivalved ,pelecypod c4 ,plane of symmetry at right angles to hinge-line2 without 8ears01 not 8,scallop-like02 commonly with opening in beak1 inequivalved ,brachiopod #b4 ,fossil tapering1 cylindrical or cone-shaped a4 ,cone-shaped1 internal longitudinal partitions or septa ,coral b4 ,tapered1 internal transverse partitions ,cephalopod c4 ,shell without internal septa or partitions 7#a47 ,shell large heavy1 longitudinal ribs4 ,cretaceous only ,rudistid 7#b47 ,shell small1 tusk-shaped1 open at both ends1 rare in ,paleozoic and ,mesozoic rocks ,scaphopod #c4 ,fossil heart-shaped1 domed or flattened2 star pattern on top ,echinoid #d4 ,fossil segmented a4 ,divided into #c lobes1 may be curled up4 ,paleozoic only ,trilobite b4 ,flattened or elongate1 resembles shrimp ,crustacean ,illustration3 ,plate #h ,fossil ,identification ,chart ,,iii ,,no ,,apparent ,,symmetry ,a4 ,shell without transverse partitions or sutures #a4 ,shell coiled like ram's horn1 low spired2 shell has two valves1 smaller flattened valve often missing4 ,in ,texas exclusively ,cretaceous ,pelecypod #b4 ,shell tightly coiled1 most have higher spire than #a1 shell smaller and not as rough as #a1 has only one valve ,gastropod ,b4 ,coiled fossils1 coiling not in one plane #a4 ,shell with transverse internal partitions or sutures a4 ,partitions always smooth1 thick shelled1 loosely and irregularly coiled1 in ,texas exclusively ,cretaceous ,caprinid b4 ,partitions 7sutures7 generally wrinkled1 regularly and tightly coiled ,cephalopod #b4 ,shell without transverse internal partitions or sutures ,gastropod #c4 ,solid spiral ridge around central axis1 resembles corkscrew ,bryozoan ,c4 ,uncoiled fossils #a4 ,fossil resembles narrow saw blade4 ,paleozoic only ,graptolite #b4 ,fossil irregularly cone-shaped1 longitudinal partitions or septa ,coral #c4 ,shell resembles clam or oyster1 nonsymmetrical ,pelecypod 7mostly oysters7 #d4 ,branching twig-like fossils a4 ,covered with minute pores or openings ,bryozoa b4 ,with evenly distributed larger openings with septa ,colonial coral #e4 ,lace-like fossils1 occur as thin sheets or films ,bryozoa #f4 ,masses of circular or polygonal tubes with septa ,colonial coral #g4 ,irregular fossils1 cylindrical with rough surface a4 ,large axial opening with thick wall1 external longitudinal ribs4 ,cretaceous only ,rudistid b4 ,solid1 no opening1 small pits or pores4 ,pennsylvanian or ,permian ,sponge ,,cataloging ,,the ,,collection ,after the fossils have been cleaned and tentatively identified1 they should be cataloged4 ,this is necessary to enable the collector to have a record of his collection and to furnish as much information as possible about each individual fossil4 ,the collecting data can be taken from the labels that were placed in each bag of fossils as they were collected1 or from the field notebook4 ,actually1 it is wise to check one against the other4 ,this information should then be entered in some type of record book and also placed on a more permanent label which is put in the tray or box with the fossil4 ,the catalog and label should contain such pertinent data as 7#a7 the scientific name of the fossil1 7#b7 the geologic formation from which the specimen was collected1 7#c7 the exact geographic location of the collecting locality1 7#d7 the name of the collector1 7#e7 the date the fossil was collected1 and 7#f7 the catalog number of the specimen4 ,the latter is usually placed in the upper right hand corner of the label 7fig4 #f7 and corresponds with a like number in the record book4 ,specimen ,no4 ,p-#ahe ,,name ,spirifer rockymontanus ,,formation ,big ,saline 7,penn47 ,,locality ,little ,brady ,creek1 ,mc,culloch ,co41 ,tex4 7#ajjj ,,ne of ,smith ranch ,house7 ,,collector ,f4 ,b4 ,plummer ,,date ,july #aicg ,illustration3 ,fig4 #f4 ,a brachiopod showing the catalog number on it1 and the accompanying label that pertains to the specimen4 ,the entries in the catalog should be numbered consecutively1 and all specimens from the same locality should bear the same number4 ,this number should be written on the fossil with ,india ink1 preferably on any remaining matrix or on some inconspicuous part of the specimen 7fig4 #f74 ,if the surface of the fossil is too coarse or porous for ink1 the catalog number can be written on a small patch of white enamel or clear nail polish painted on the specimen4 ,after the ink has dried it should be coated with a dab of clear shellac or clear nail polish to help preserve the number4 ,if each specimen is numbered1 it can easily be identified even if it should become separated from its label4 ,,how ,,fossils ,,are ,,used ,fossils are useful in a number of different ways1 for each specimen provides some information about when it lived1 where it lived1 and how it lived4 ,fossils are very important1 for example1 in tracing the development of the plants and animals of our earth4 ,this is possible because the fossils in the older rocks are usually primitive and relatively simple2 but a study of similar specimens that lived in later geologic time shows that the fossils become progressively more complex and more advanced in the younger rocks4 ,some fossils1 for example1 the reef-building corals1 appear to have always lived under much the same conditions as they live today4 ,hence1 it is reasonably certain that the rocks containing fossil reef corals found in place 7that is1 where they were originally buried71 were deposited in warm1 fairly shallow1 salt water4 ,by studying the occurrence and distribution of such marine fossils1 it is possible to outline the location and extent of prehistoric seas4 ,moreover1 the type of fossils present will frequently give some indication as to the bottom conditions1 depth1 temperature1 and salinity of these ancient bodies of water4 ,probably the most important use of fossils is for purposes of correlation--the process of demonstrating that certain rock layers are closely related to each other4 ,by correlating or 8matching0 the beds containing specific fossils1 it is possible to determine the distribution of geologic units of similar age4 ,some fossils have a very limited vertical or geologic range and a wide horizontal or geographic range4 ,in other words1 they lived but a relatively short period in geologic time but were rather widely distributed during their relatively short life4 ,such fossils are known as index fossils or guide fossils and are especially useful in correlation because they are normally only associated with rocks of one certain age4 ,illustration3 ,fig4 #g4 ,sketches of two types of micropaleontological slides4 7a7 ,multiple space faunal slide4 7b7 ,single-hole slide4 ,microfossils are often very valuable as guide fossils for the petroleum geologist4 ,the micropaleontologist washes the well cuttings from the drill hole and separates the tiny fossils from the surrounding rocks4 ,the specimens are then mounted on special slides 7fig4 #g7 and studied under the microscope4 ,information derived from these fossils often provides valuable data on the age of the subsurface formation and the possibilities of oil production4 ,microfossils are particularly valuable in the oil fields of the ,gulf ,coast region of ,texas4 ,in fact1 some of the oil-producing zones in this area have even been named for certain key genera of microfossils4 ,for example1 the 8het0 zone of ,oligocene age 7geologic time scale1 ,pl4 #a7 is named for the genus ,heterostegina1 which is a tiny one-celled animal4 ,other microfossils1 such as fusulinids1 ostracodes1 spores1 and pollens1 are also used to identify subsurface formations in many other parts of the ,state4 ,plant fossils are very useful as climatic indicators but are not too reliable for purposes of age determination4 ,they do1 however1 provide much information about the development of plants throughout geologic time4 ,,geologic ,,history ,the geologic history of our earth has been recorded primarily in marine sedimentary rocks1 and this record indicates that our earth is very old and that life has been present for many millions of years4 ,the earth is not only extremely old 7more than #c billion years of age71 but it has also undergone many changes which have taken place slowly but steadily and have greatly affected both the earth and its inhabitants4 ,the earth's physical features have not always been as they are seen today4 ,geologic research has shown that mountains now occupy the sites of ancient seas1 and that coal is being mined where swamps existed millions of years ago4 ,furthermore1 there is much evidence to indicate that plants and animals have also undergone great change4 ,the trend of this organic change is1 in general1 toward more complex and advanced forms of life1 but some forms have remained virtually unchanged and others have become extinct4 ,in order to interpret geologic history1 the earth scientist must attempt to gather evidence of the great changes in climate1 geography1 and life that took place in the geologic past4 ,the record of these changes can be found in the rocks1 and here is found the story of the various events in earth history4 ,,geologic ,,column ,,and ,,time ,,scale ,in order to discuss fossils and the age of the rocks containing them1 it is necessary to become familiar with the geologic column and the geologic time scale 7,pl4 #a74 ,the geologic column refers to the total succession of rocks1 from the oldest to most recent1 that are found either locally or in the entire earth4 ,thus1 the geologic column of ,texas includes all rock divisions known to be present in this ,state4 ,by referring to the geologic column previously worked out for any given area1 the geologist can determine what type of rocks he might expect to find in that particular region4 ,the geologic time scale is composed of units which represent intervals of geologic time1 during which were deposited the rocks represented in the geologic column4 ,these time units are used by the geologist to date the events that have taken place in the geologic past4 ,the largest unit of geologic time is an era1 and each era is divided into smaller time units called periods4 ,a period of geologic time is divided into epochs1 which1 in turn1 may be subdivided into still smaller units4 ,the geologic time scale might be roughly compared to the calendar in which the year is divided into months1 months into weeks1 and weeks into days4 ,unlike years1 however1 geologic time units are arbitrary and of unequal duration1 and the geologist cannot be positive about the exact length of time involved in each unit4 ,the time scale does1 however1 provide a standard by which he can discuss the age of fossils and their surrounding rocks4 ,by referring to the time scale it may be possible1 for instance1 to state that a certain event occurred during the ,paleozoic era in the same sense that one might say that something happened during the ,american ,revolution4 ,there are five eras of geologic time1 and each has been given a name that is descriptive of the degree of life development that characterizes that era4 ,hence1 ,paleozoic means 8ancient-life10 and the era was so named because of the relatively simple and ancient stage of life development4 ,the eras1 a guide to their pronunciation1 and the literal translation of each name is shown below4 ,cenozoic 7,,see-no-zo-ic7--8recent-life0 ,mesozoic 7,,mes-o-zo-ic7--8middle-life0 ,paleozoic 7,,pay-lee-o-zo-ic7--8ancient-life0 ,proterozoic 7,,pro-ter-o-zo-ic7--8primitive-life0 ,archeozoic 7,,ar-kee-o-zo-ic7--8beginning-life0 ,archeozoic and ,proterozoic rocks are commonly grouped together and referred to as ,precambrian in age4 ,the ,precambrian rocks have been greatly contorted and metamorphosed1 and the record of this portion of earth history is most difficult to interpret4 ,precambrian time represents that portion of geologic time from the beginning of earth history until the deposition of the earliest fossiliferous ,cambrian strata4 ,if the earth is as old as is believed1 ,precambrian time may represent as much as #he percent of all geologic time4 ,the oldest era is at the bottom of the list because this part of geologic time transpired first and was then followed by the successively younger eras which are placed above it4 ,therefore1 the geologic time scale is always read from the bottom of the chart upward4 ,this is1 of course1 the order in which the various portions of geologic time occurred and during which the corresponding rocks were formed4 ,as mentioned above1 each of the eras has been divided into periods1 and most of these periods derive their names from the regions in which the rocks of each were first studied4 ,for example1 the ,pennsylvanian rocks of ,north ,america were first studied in the ,state of ,pennsylvania4 ,the ,paleozoic era has been divided into seven periods of geologic time4 ,with the oldest at the bottom of the list1 these periods and the source of their names are3 ,permian 7,,pur-me-un7--from the ,province of ,perm in ,russia ,pennsylvanian 7pen-sil-,,vain-yun7--from the ,state of ,pennsylvania ,mississippian 7miss-i-,,sip-i-un7--from the ,upper ,mississippi ,valley ,devonian 7de-,,vo-ni-un7--from ,devonshire1 ,england ,silurian 7si-,,loo-ri-un7--for the ,silures1 an ancient tribe of ,britain ,ordovician 7or-doe-,,vish-un7--for the ,ordovices1 an ancient tribe of ,britain ,cambrian 7,,kam-bri-un7--from the ,latin word ,cambria1 meaning ,wales ,the ,carboniferous period in ,europe includes the ,mississippian and ,pennsylvanian periods of ,north ,america4 ,although this classification is no longer used in the ,united ,states1 the term ,carboniferous will be found in many of the earlier geological publications and on many of the earlier geologic maps4 ,the periods of the ,mesozoic era and the source of their names are3 ,cretaceous 7cre-,,tay-shus7--from the ,latin word creta1 meaning chalky ,jurassic 7joo-,,ras-ik7--from the ,jura ,mountains of ,europe ,triassic 7try-,,ass-ik7--from the ,latin word triad1 meaning three ,in ,texas1 the ,cretaceous has two divisions1 known as either ,lower ,cretaceous and ,upper ,cretaceous or as ,comanche series and ,gulf series1 respectively4 ,these designations are for rocks of nearly equivalent age1 and both sets of terms have been used by geologists and in publications4 ,in this handbook1 both sets of terms are used interchangeably1 that is1 ,lower ,cretaceous and_/or ,comanche series and ,upper ,cretaceous and_/or ,gulf series4 ,the ,cenozoic periods derived their names from an old outdated system of classification which divided all of the earth's rocks into four groups4 ,the two divisions listed below are the only names of this system which are still in use3 ,quaternary 7kwah-,,tur-nuh-ri7 ,tertiary 7,,tur-shi-ri7 ,while the units discussed above are the major divisions of geologic time1 the geologist usually works with smaller units of rocks called formations4 ,a geologic formation is identified and established on the basis of definite physical and chemical characteristics of the rocks4 ,formations are usually given geographic names which are combined with the type of rock that makes up the bulk of the formation4 ,for example1 the ,beaumont clay was named from clay deposits that are found in and around ,beaumont1 ,texas4 ,,the ,,geology ,,of ,,texas ,the geologic history of ,texas1 like the geologic history of the rest of the earth1 is recorded primarily in marine sedimentary rocks4 ,these rocks provide some knowledge of the early geography and the first inhabitants of what is now the ,state of ,texas4 ,most of these rocks were formed from sediments deposited in shallow seas which covered parts of the ,state at various times in earth history4 ,by studying these rocks and their relations to each other1 geologists have established a geologic column for ,texas4 ,physiography ,in order to discuss the distribution and exposures of the rocks of ,texas1 it is helpful to be familiar with the physiography of the ,state4 ,physiography deals with the study of the origin and description of land forms1 such as mountains1 valleys1 and plains4 ,plate #i is a map of ,texas which shows the major physiographic provinces within the ,state4 ,the majority of the land forms in ,texas have been produced by the processes of erosion attacking the structural features of an area4 ,certain other land forms may be related to the effects of igneous activity which resulted in the accumulation of large masses of igneous rocks4 ,the ,davis ,mountains are an example of surface features produced in this manner4 ,in discussing the physiography of ,texas1 three major physiographic provinces will be recognized4 ,these are 7#a7 the ,trans-,pecos region1 7#b7 the ,texas ,plains1 and 7#c7 the ,gulf ,coastal ,plain 7,pl4 #i74 ,,trans-,,pecos ,,region ,the ,trans-,pecos region1 located in the westernmost part of the ,state1 is an area of mountains and plateaus with broad basins between the major mountain ranges4 ,many different types of rocks are exposed in ,trans-,pecos ,texas and these include marine1 fresh-water1 and terrestrial deposits4 ,in many areas igneous rocks flowed out on the surface and now overlie sedimentary rocks4 ,there are also many places where igneous rocks have been injected into the surrounding rocks1 and these igneous rocks have been exposed by later erosion4 ,included within this area is the ,van ,horn uplift of southern ,hudspeth and ,culberson counties1 the ,solitario uplift of southern ,presidio and ,brewster counties1 and the ,marathon uplift of northeast ,brewster ,county4 ,this region also includes the ,big ,bend area of ,texas1 a part of which has been set aside as a ,national ,park where many interesting and important geological features may be seen4 ,the ,trans-,pecos region is one of rugged topography with elevations as high as #h1gjj feet1 at ,guadalupe ,peak in the ,guadalupe ,mountains of northern ,culberson ,county1 and as low as #a1ejj feet1 in the ,rio ,grande valley4 ,numerous invertebrate fossils occur in the ,cretaceous limestones and shales of the ,trans-,pecos region and in the ,paleozoic rocks of the ,marathon uplift4 ,the ,gaptank formation of ,pennsylvanian age and the ,permian reef limestones of the ,glass ,mountains are especially fossiliferous4 ,in addition1 many vertebrate fossils have been collected in ,trans-,pecos ,texas1 particularly in and around ,big ,bend ,national ,park4 ,,texas ,,plains ,the plains of ,texas are broad expanses of country with very little surface relief4 ,most of the plains support grasses and some have wooded areas1 particularly along stream valleys4 ,the plains of the northwestern part of the ,state have been subdivided as follows4 ,high ,plains ,this area 7,pl4 #i71 often called 8the caprock10 is an elevated plateau which rises above the rolling plains which surround it4 ,the ,high ,plains are bounded by the ,pecos ,river valley on the south1 southeast1 and west and by the ,north-,central ,plains on the east4 ,the surface of the ,high ,plains is very flat and characterized by a sparse cover of grasses and few trees4 ,the surface strata consist largely of unconsolidated deposits of sands and gravels of ,quaternary and ,tertiary age1 with remnants of ,lower ,cretaceous limestones along the southern margin4 ,the rocks of the ,high ,plains are mostly unfossiliferous1 but mammalian remains have been found at several localities4 ,illustration3 ,plate #i ,physiographic map of ,texas4 ,,high ,,plains ,,north-,,central ,,plains ,,grand ,,prairie ,,trans-,,pecos ,,texas ,,van ,,horn ,,uplift ,,the ,,big ,,bend ,,area ,,solitario ,,uplift ,,marathon ,,uplift ,,edwards ,,plateau ,,llano ,,uplift ,,balcones ,,fault ,,zone ,,gulf ,,coastal ,,plain ,north-,central ,plains ,surface strata of the ,north-,central ,plains 7,pl4 #i7 are westward-dipping ,pennsylvanian1 ,permian1 and ,triassic rocks4 ,present also are extensive exposures of ,quaternary sands and gravels which trend north-south across the central portion of the region4 ,the area is bounded on the west by the ,high ,plains1 on the east by the ,grand ,prairie1 and on the south by the ,edwards ,plateau and ,llano uplift4 ,many vertebrate fossils have been collected from the ,permian and ,triassic rocks of this area4 ,there are also many excellent outcrops of fossiliferous ,pennsylvanian formations in the ,north-,central ,plains region4 ,edwards ,plateau ,the ,edwards ,plateau 7,pl4 #i7 is located in south-central ,texas and is bounded on the south by the ,balcones fault zone and on the north by the ,north-,central ,plains4 ,the surface of the area is typically flat with a gentle slope to the south4 ,the rocks of the ,edwards ,plateau consist primarily of ,lower ,cretaceous limestones and shales1 many of which are very fossiliferous4 ,grand ,prairie ,this area 7,pl4 #i7 has a relatively flat surface but there are areas of gently rolling hills4 ,the eastern boundary of the ,grand ,prairie is marked partly by the ,balcones fault zone4 ,north of ,mc,lennan ,county1 however1 the ,balcones fault zone is not expressed at the surface and in this area the eastern boundary is defined by the western edge of the ,woodbine exposures4 ,upper and ,lower ,cretaceous rocks occur at the surface and dip to the southeast2 many of these rocks contain a large number of invertebrate fossils4 ,llano ,uplift ,the ,llano uplift 7,pl4 #i7 is located in the central part of the ,state where ,precambrian igneous and metamorphic rocks and sedimentary rocks of early ,paleozoic age occur on the surface4 ,the area1 which now appears as a basin-shaped depression1 was at one time covered by ,lower ,cretaceous rocks and perhaps also by ,devonian1 ,mississippian1 and ,pennsylvanian strata4 ,these have since been removed by erosion4 ,the east1 south1 and west sides of the uplift are surrounded by ,lower ,cretaceous rocks1 and the northern margin is marked by the ,mississippian and ,pennsylvanian formations of the ,north-,central ,plains4 ,the area is1 in general1 composed of unfossiliferous rocks1 but some invertebrate fossils 7primarily trilobites and brachiopods7 have been collected4 ,,gulf ,,coastal ,,plain ,the ,gulf ,coastal ,plain 7,pl4 #i7 is composed of ,cretaceous1 ,tertiary1 and ,quaternary rocks and includes the eastern1 southeastern1 and southern portions of the ,state4 ,the rocks of the area consist of sands1 clays1 shales1 and limestones4 ,the ,texas ,gulf ,coastal ,plain is bounded on the north and west by the ,balcones fault zone1 on the south and southwest by the ,gulf of ,mexico1 and extends eastward into ,arkansas and ,louisiana4 ,the region has broad river valleys and uplands of low relief1 but there is an increase in relief toward the interior of the ,state4 ,the surface of the area slopes gradually toward the ,gulf and successively younger formations are encountered gulfward4 ,the rocks of the ,texas ,gulf ,coastal ,plain are relatively unfossiliferous1 but many of the ,upper ,cretaceous rocks contain fossils4 ,in the central portion of the region some marine formations of ,tertiary age locally contain well-preserved invertebrate fossils4 ,geology ,geologic studies of the ,state of ,texas have indicated the presence of rocks formed during every era and period of geologic time4 ,these range from the ,precambrian granites of the ,llano uplift to the ,quaternary gravels of the ,high ,plains4 ,illustration3 ,plate #aj ,,generalized ,,geologic ,,map ,,of ,,texas ,modified from ,geologic ,map of ,texas1 #aicc ,one of the best ways to become acquainted with the geology of ,texas is to study the geologic map of the ,state 7,pl4 #aj74 ,a geologic map shows the distribution and age of surface rocks and may also indicate what kind of geologic structures are present4 ,the types of rocks that crop out at the surface may be shown by means of symbols1 colors1 or patterns1 and these are explained by a legend which accompanies the map4 ,on ,plate #aj1 colors are used to show the distribution and geologic age of the surface rocks of ,texas4 ,reference to this map will give the collector some idea of the age of the fossils that might be found in a given area4 ,some special geologic maps may have the location of geologic structures and formation contacts indicated by means of symbols1 such as dashed lines1 arrows1 and similar special markings4 ,however1 the map included in this publication does not show any of these special markings4 ,,precambrian ,,rocks ,the ,precambrian rocks of ,texas are composed of igneous and metamorphic rocks and some sedimentary rocks4 ,most of the ,precambrian outcrops are in the ,llano uplift and ,el ,paso and ,van ,horn regions4 ,alterations produced by vast amounts of time1 heat1 and pressure have obliterated any trace of fossils that may have been present in these rocks4 ,with the exception of some questionable primitive plants collected in the ,van ,horn region1 no ,precambrian fossils have been reported from ,texas4 ,,paleozoic ,,rocks ,rocks of ,paleozoic age are widespread in ,texas1 and rocks of each period are well exposed4 ,outcrops are found in the ,llano uplift1 ,north-,central ,plains1 and ,trans-,pecos region4 ,the most extensive exposures are of ,pennsylvanian and ,permian age1 and the former are highly fossiliferous in parts of the ,north-,central ,plains4 ,cambrian ,rocks of late ,cambrian age are exposed in the ,llano1 ,marathon1 and ,solitario uplifts1 and the ,franklin ,mountains near ,el ,paso4 ,these are sedimentary rocks consisting of conglomerates1 sandstones1 shales1 limestones1 and some dolomites4 ,some of these formations are relatively fossiliferous1 but the specimens are commonly fragmental and very poorly preserved4 ,fossils that are apt to be found in the ,cambrian rocks of the ,llano uplift include brachiopods1 gastropods1 trilobites1 and small rounded objects believed to have been formed by algae 7primitive one-celled plants74 ,in other parts of the ,state1 ,cambrian rocks are sparsely fossiliferous and the fossils consist primarily of fragmental brachiopods1 trilobites1 and algae4 ,ordovician ,ordovician outcrops are present in the ,llano uplift of central ,texas and in the ,marathon1 ,solitario1 ,el ,paso1 and ,van ,horn regions of ,trans-,pecos ,texas4 ,these are sedimentary rocks and consist largely of sandstones1 cherts1 limestones1 and dolomites4 ,although some of the ,ordovician formations are fossiliferous1 they are seldom collected by amateur paleontologists because they are exposed in relatively inaccessible places and the fossils are usually poorly preserved4 ,ordovician fossils reported from ,texas include sponges1 corals1 brachiopods1 gastropods1 cephalopods1 and trilobites4 ,in addition1 the ,marathon formation of the ,marathon uplift contains large numbers of well-preserved graptolites 7fig4 #bd1 p4 #hf74 ,silurian ,the ,silurian of ,texas is poorly represented in surface exposures1 and only one formation1 the ,fusselman1 has been described4 ,the ,fusselman crops out in the ,el ,paso and ,van ,horn regions where it is a white dolomitic limestone4 ,fossils are not abundant in this formation1 but brachiopods and corals have been collected at a few localities4 ,devonian ,devonian rocks are best developed in ,trans-,pecos ,texas1 especially in the ,marathon1 ,el ,paso1 and ,van ,horn regions4 ,in addition to the ,trans-,pecos exposures1 there are minor outcrops of ,devonian rocks in the ,llano uplift of central ,texas4 ,fossils are rare and fragmental in the ,trans-,pecos exposures and consist primarily of radiolarians and brachiopods4 ,the ,devonian rocks of central ,texas are predominantly calcareous and1 although the material is usually poorly preserved1 many fossils have been collected from them4 ,these include bryozoans1 corals1 brachiopods1 gastropods1 and trilobites4 ,conodonts and fragments of primitive armored fishes 7,pl4 #cg7 have also been reported4 ,mississippian ,mississippian rocks are exposed in the ,llano region and in the ,hueco ,mountains of the ,trans-,pecos area4 ,the ,trans-,pecos rocks primarily contain brachiopods with some bryozoans and gastropods4 ,the central ,texas ,mississippian rocks are much more fossiliferous and some of the material is well preserved4 ,fossils reported from this area include brachiopods 7,pl4 #ag71 crinoids1 gastropods1 cephalopods1 trilobites1 and ostracodes4 ,pennsylvanian ,pennsylvanian rocks are well represented in ,texas and are exposed in the ,llano uplift1 north-central ,texas1 and ,trans-,pecos ,texas4 ,in ,trans-,pecos ,texas fossiliferous rocks crop out in the ,hueco and ,diablo ,mountains4 ,fossils found in this area are algae1 fusulinids1 corals1 brachiopods1 pelecypods1 gastropods1 cephalopods1 and crinoids4 ,there is also a thick section of ,pennsylvanian rocks in the ,marathon uplift1 but only one formation1 the ,gaptank1 is very fossiliferous4 ,it contains many fossils including fusulinids1 sponges1 corals1 bryozoans1 brachiopods1 gastropods1 pelecypods1 cephalopods1 and crinoids4 ,certain ,pennsylvanian strata in the ,llano region are very fossiliferous1 and the material is well preserved4 ,the more abundant forms are fusulinids1 corals1 brachiopods1 gastropods1 pelecypods1 cephalopods1 and crinoids4 ,probably the best ,pennsylvanian collecting areas are to be found in north-central ,texas4 ,here the thick marine limestones and shales contain large numbers of well-preserved invertebrate fossils1 and the terrestrial or shallow marine strata have yielded an abundance of plant fossils4 ,invertebrate fossils are apt to be found along the banks of streams and gullies and in railroad and highway cuts4 ,many of the limestones bear large numbers of fusulinids or crinoid stems1 and the shales may contain many corals1 brachiopods1 and mollusks4 ,the best collecting will1 of course1 be found where the rocks have been sufficiently weathered4 ,illustration3 ,fig4 #h4 ,sketch of typical crinoidal limestone from the ,pennsylvanian of north ,texas4 ,typical invertebrate fossils are foraminifera 7principally fusulinids71 corals 7especially the solitary or 8horn0 corals71 brachiopods1 bryozoans 7the lacy and branching types are most common71 pelecypods1 gastropods 7exhibiting a variety of coiling71 cephalopods 7nautiloids and goniatites predominate71 and crinoids1 which in many areas are found in thick crinoidal limestones 7fig4 #h74 ,some typical ,pennsylvanian fossils are illustrated in ,plates #ad1 #ae1 #ag1 #ah1 #ai1 #bj1 #ba1 #bd1 #cb1 and #ce4 ,permian ,permian rocks are found in widely separated areas in ,texas4 ,the best exposed section of marine ,permian rocks is found in the ,glass ,mountains of ,brewester ,county1 and many of these rocks are very fossiliferous4 ,the original shell material of some of the ,permian fossils of this area has been replaced by siliceous material which is very well preserved4 ,these silicified fossils are removed from the limestone by solution in acid1 and some most remarkable specimens have been recovered in this manner 7,pl4 #c74 ,brachiopods are the most common fossils1 but corals1 bryozoans1 and mollusks have also been recovered4 ,extensive ,permian exposures occur also in the central part of the ,north-,central ,plains region4 ,these rocks were formed from sediments of both marine and continental origin and some of them are fossiliferous4 ,the marine rocks contain a variety of invertebrate fossils including brachiopods1 pelecypods1 gastropods1 and ammonoids4 ,those rocks representing terrestrial deposits contain vertebrate remains at many localities1 and numerous amphibians and primitive reptiles 7,pl4 #dj7 have been collected from them4 ,,mesozoic ,,rocks ,mesozoic rocks occur over a wide area of ,texas and include exposures of ,triassic1 ,jurassic1 and ,cretaceous age4 ,many of the ,upper and ,lower ,cretaceous outcrops are quite fossiliferous and easily accessible and thus of considerable interest to many amateur collectors4 ,triassic ,triassic rocks crop out in parts of the ,high ,plains1 the ,glass ,mountains of ,trans-,pecos ,texas1 and parts of ,pecos1 ,crockett1 ,upton1 ,reagan1 and ,glasscock and other west ,texas counties4 ,these are predominantly nonmarine rocks consisting of conglomerates1 sandstones1 shales1 and some gypsum beds4 ,triassic fossils are almost exclusively vertebrates1 although some poorly preserved plant and invertebrate remains have been reported4 ,fossil vertebrates of the ,texas ,triassic include phytosaurs 7,pl4 #db71 crocodiles1 amphibians1 and fish4 ,jurassic ,in ,texas1 surface exposures of ,jurassic rocks are known only from ,malone ,mountain in southwestern ,hudspeth ,county4 ,the rocks there are limestones1 shales1 sandstones1 and conglomerates4 ,fossils reported from that locality include marine and fresh-water pelecypods1 fresh-water gastropods1 and ammonites4 ,cretaceous ,rocks of ,cretaceous age are widely distributed in ,texas and represent one of the more important rock systems of the ,state4 ,cretaceous outcrops occur in central ,texas1 north ,texas1 the ,edwards ,plateau1 parts of the ,high ,plains1 the ,gulf ,coastal ,plain1 and ,trans-,pecos ,texas4 ,as mentioned earlier1 the ,texas ,cretaceous has been divided into the ,lower ,cretaceous 7,comanche series7 and ,upper ,cretaceous 7,gulf series74 ,these rocks consist primarily of marls 7a type of calcareous clay71 shales1 chalks1 and limestones1 but sands and conglomerates also occur4 ,cretaceous rocks occur on the surface of about #bh percent of ,texas1 and many of the larger cities of the ,state are situated on ,cretaceous strata4 ,many of the ,gulf and ,comanche formations contain fossils which are of interest both to amateur and professional paleontologists4 ,because of their wide distribution in and near large population centers1 ,cretaceous outcrops can be conveniently visited by many amateur fossil collectors4 ,the fossils are usually abundant and varied1 and some are well preserved4 ,although numerous kinds of fossils may be collected1 the more common forms are cephalopods1 pelecypods1 gastropods1 and echinoids4 ,some of the more typical ,cretaceous fossils are shown in ,plates #af1 #ba1 #be-bh1 #cb1 #cc1 #ce1 and #cf4 ,cretaceous fossils are more commonly found in shales and chalky limestones4 ,fossiliferous outcrops of these rocks can be found along many streams1 roads1 and highways of central ,texas1 north ,texas1 and the ,edwards ,plateau4 ,outcrops which have been weathered are more likely to provide good collecting4 ,in general1 collecting is poor in areas covered with heavy vegetation or recent stream deposits4 ,good collecting localities are outcrops which have a fairly steep slope with a covering of weathered rock material and a minimum of vegetation4 ,one should move slowly from the base of the slope upward while searching the ground for any evidence of fossils1 and particular attention should be given to any small gullies since these often contain fossils that have been washed out of upper beds in the exposure4 ,,cenozoic ,,rocks ,cenozoic rocks are widespread in ,texas but occur primarily in a broad belt along the ,gulf ,coastal ,plain4 ,in addition1 there are exposures of nonmarine ,cenozoic strata in the ,high ,plains1 ,north-,central ,plains1 and ,trans-,pecos region4 ,there are also many exposures of ,cenozoic igneous rocks in ,trans-,pecos ,texas4 ,rocks of ,cenozoic age occur in more than one-third of ,texas and consist of conglomerates1 sands1 clays1 and some limestone and lignite beds4 ,tertiary ,extensive exposures of ,tertiary rocks trend northeast-southwest in a broad band across the ,gulf ,coastal ,plain area4 ,these strata1 consisting of sands1 clays1 and poorly consolidated limestones1 are underlain by ,cretaceous rocks4 ,invertebrate fossils are common in certain ,tertiary formations and pelecypods1 gastropods1 and corals are the predominant forms4 ,in general1 however1 fossiliferous exposures are of local occurrence and most of the ,tertiary formations are unfossiliferous4 ,those ,tertiary invertebrates that are present1 however1 are often well preserved and represent many interesting types 7,pls4 #af1 #bb1 #bc1 #bi1 #cj1 #ca74 ,tertiary invertebrate fossils are commonly found in sands1 clays1 and marls4 ,many of these sands and marls have a green color which is due to the presence of glauconite 7a green mineral containing iron and closely related to the micas74 ,at certain localities on the ,gulf ,coastal ,plain the glauconite marls and sands of the ,weches and ,crockett formations contain large numbers of well-preserved clams1 snails1 and corals4 ,fossiliferous exposures of ,tertiary rocks are sometimes found in road cuts1 but better exposures may be found along the banks of rivers and creeks4 ,certain bluffs along the ,brazos1 ,sabine1 and ,trinity rivers are well-known ,tertiary fossil collecting localities4 ,many of these better localities are listed in some of the ,bureau of ,economic ,geology bulletins included in the bibliography of this publication 7pp4 #aji-aaj74 ,quaternary ,quaternary deposits of ,pleistocene age 7geologic time scale1 ,pl4 #a7 are found in many parts of ,texas and consist of sands1 clays1 and gravels4 ,these rocks are distributed along the ,gulf ,coast in a belt from #ej to #ajj miles wide4 ,they occur also as stream terraces in the ,edwards ,plateau and ,north-,central ,plains regions4 ,in addition1 ,quaternary sands and gravels are widely distributed over the surface of much of ,trans-,pecos ,texas4 ,there are also fossiliferous ,pleistocene strata in the ,high ,plains region4 ,invertebrate fossils are rare in ,pleistocene rocks1 but some fresh-water and terrestrial mollusks occur4 ,vertebrate remains1 however1 are abundant in many localities1 and large numbers of horses1 camels1 mammoths1 and other mammals 7,pls4 #df-di7 have been collected4 ,fossil bones and teeth 7figs4 #be1 #bf1 p4 #ajd7 are commonly found in the gravels and sands of many of the river terraces of the ,state4 ,,main ,,types ,,of ,,fossils ,the beginning fossil collector is usually amazed by the many different plants and animals that have left some trace of their existence4 ,in order to understand these different types of prehistoric life1 it is necessary to know something about the organisms that are living today4 ,this handbook discusses the more important groups of plants and animals which have left some sort of paleontological record1 and each major group begins with a discussion of the more simple organisms and continues through the more advanced forms4 ,because scientific workers do not always agree on exactly the same classification1 the system adopted in this handbook contains the latest ideas of several workers4 ,it is simple enough to understand1 yet complete enough to help one know and classify his fossils4 ,it should be noted that this classification may differ in some respects from that of certain older paleontological publications4 ,therefore1 it has seemed advisable to list other names for some of the groups that are discussed4 ,in some instances1 the brief descriptions and illustrations of each group will enable the collector to make a preliminary identification of his fossils4 ,for more detailed information about each group1 the reader should refer to 8,books ,about ,fossils0 7pp4 #ajh-aaj74 ,this part of the handbook begins with a brief summary of the major groups of the plant kingdom1 followed by a discussion of the characteristics and relative paleontological importance of the various invertebrate animals4 ,emphasis is placed on the invertebrates because this type of fossil is most commonly collected by the amateur4 ,finally1 there is a general review of the vertebrates4 ,,plant ,,fossils ,plant fossils are usually fragmental and poorly preserved1 and this tends to discourage most amateurs from an active interest in paleobotany4 ,however1 in spite of these problems1 much is known of the evolution of plants1 and plant fossils provide much information about life of the past4 ,in addition1 certain plants are of considerable value as indicators of ancient climatic conditions1 and their remains have played a large part in the formation of vast coal deposits4 ,classification of the ,plant ,kingdom ,in the following classification only the larger taxonomic groups are discussed4 ,notice that the term division has been used in place of the term phylum as used in the animal kingdom4 ,this usage is now preferred by many botanists and paleobotanists4 ,,division ,,thallophyta ,thallophytes are simple plants without roots1 stems1 or leaves4 ,they include the fungi1 algae1 and diatoms 7,pl4 #ab74 ,diatoms are microscopic fossils that are found in many of the rocks of ,texas1 and they are quite abundant in ,recent sediments as well4 ,certain of the ,paleozoic limestones of central ,texas contain banded spherical masses of algae called 8algal biscuits40 ,although not particularly useful fossils1 thallophytes have a long geologic history and are known in rocks ranging from ,precambrian to ,recent in age4 ,,division ,,bryophyta ,the bryophytes are simple rootless plants and include the mosses and liverworts4 ,although more complex1 the bryophytes resemble the algae in some respects4 ,they are uncommon fossils1 but undoubted bryophytes 7liverworts7 have been reported from rocks as old as ,mississippian4 ,,division ,,tracheophyta ,this division has been divided into four subdivisions1 among which are many of the more common living and fossil plants4 ,such important plants as the ferns1 evergreens1 hardwood trees1 and the flowering plants are all tracheophytes4 ,among the more common and abundant fossil tracheophytes are the ferns1 cycads1 and ,gingko1 in addition to such important 8coal plants0 as the scale trees1 club mosses1 and scouring rushes 7,pls4 #ab1 #ac74 ,the latter commonly occur in many of the world's great coal deposits1 and their remains make up a large part of the coal4 ,plant fossils of this type may be collected in the dumps around some of the abandoned coal mines in north-central ,texas and from other ,pennsylvanian rocks in north and ,trans-,pecos ,texas4 ,illustration3 ,plate #aa ,,geologic ,,range ,,of ,,the ,,major ,,groups ,,of ,,plants ,,and ,,animals ,the bands give some indication of the geologic range and relative abundance of the major groups of plants and animals4 ,an increase in the width of the range band corresponds to a relative increase in numbers during the corresponding portion of geologic time4 ,,precambrian ,,paleozoic ,,cambrian ,,ordovician ,,silurian ,,devonian ,,mississippian ,,pennsylvanian ,,permian ,,mesozoic ,,jurassic ,,cretaceous ,,cenozoic ,thallophyta ,bryophyta ,tracheophyta ,protozoa ,porifera ,coelenterata ,bryozoa ,brachiopada ,mollusca ,annelida ,arthropoda ,echinodermata ,chordata ,illustration3 ,plate #ab ,,fossil ,,plants ,illustration3 ,,thallophytes ,,diatoms #ijj ,,algae #djj ,illustration3 ,,tracheophytes ,,lepidodendron ,,sigillaria ,illustration3 ,plate #ac ,,fossil ,,plants ,,tracheophytes ,,neuropteris ,,psilophyton ,,calamites ,,amelanchier ,,cordaites ,,gingko ,fairly well-preserved plant remains may also be collected from the ,woodbine group of the ,upper ,cretaceous in north ,texas1 and fossil wood1 most of it silicified1 has been reported from rocks of almost all ages and in almost every section of the ,state4 ,in addition1 some of the carbonaceous clays and shales of east ,texas contain large assemblages of plant leaves1 which in some places are well preserved4 ,it is also possible to find the fossilized remains of seeds1 spores1 and pollen4 ,because of their small size1 these minute remains are not destroyed by the drill bit and can be brought out of deep wells without being damaged1 and for this reason they are a valuable tool for the micropaleontologist4 ,,animal ,,fossils ,the fossilized remains of animals are very common in many of the sedimentary rocks of ,texas4 ,these remains are of many different kinds and represent the fossils of such diverse organisms as the shell of a tiny one-celled animal or the bones or tusk of a huge elephant4 ,the fossils most commonly found1 however1 are the remains of invertebrate animals such as clams1 snails1 and corals1 and it is this type of fossil that attracts the interest of most amateur collectors4 ,it is not always easy to tell whether certain organisms are plants or animals1 and because of this some scientists have suggested that these 8in-betweens0 be placed in a separate kingdom--the ,protista4 ,the protistans are primarily unicellular organisms and are represented by such forms as bacteria1 algae1 diatoms1 and the protozoans 7see below74 ,but in this publication1 only the plant and animal kingdoms are recognized4 ,phylum ,protozoa ,this phylum is composed of simple one-celled animals many of which have no shell or external body covering4 ,some1 however1 have external hard parts that can become fossilized1 and these forms are quite useful microfossils4 ,,class ,,sarcodina4-- ,this class contains a group of one-celled animals which may secrete an exoskeleton 7external protective covering7 of chitin1 silica1 or calcium carbonate4 ,included in this class are foraminiferans 7commonly called forams7 and radiolarians4 ,order ,foraminifera4-- ,members of this order secrete tiny chambered shells which are very useful microfossils4 ,the forams are predominantly marine organisms and have shells composed of chitin1 silica1 or calcium carbonate4 ,in addition1 some forms construct a shell of sand grains or some other material which is cemented together by a sticky substance that is secreted by the animal4 ,forams are very abundant in the rocks of ,texas and particularly so in rocks of ,mesozoic and ,cenozoic age4 ,the most numerous and easily observed ,paleozoic foraminiferans are the fusulinids 7fig4 #i;a71 and their small spindle-shaped remains are very abundant in many of the ,pennsylvanian limestones of north-central and ,trans-,pecos ,texas4 ,some typical ,texas forams are illustrated in figure #i4 ,order ,radiolaria4-- ,the radiolarians 7fig4 #aj7 have delicate spine-covered shells composed of silica1 and their remains are very abundant in certain recent marine sediments4 ,they may also be found as fossils and have been reported from ,devonian and ,permian rocks in ,trans-,pecos ,texas1 and probable radiolarians have been reported from still younger beds4 ,illustration3 ,fig4 #i4 ,typical ,texas ,foraminifera 7all greatly enlarged74 7a7 ,fusulina 7,pennsylvanian74 7b7 ,robulus4 7c7 ,globigerina4 7d7 ,frondicularia4 7b-d1 ,cretaceous74 ,illustration3 ,fig4 #aj4 ,typical radiolarians 7greatly enlarged74 7a7 ,actinomma 7,recent74 7b7 ,porodiscus 7,eocene74 ,phylum ,porifera ,these are sponges and are the simplest of the many-celled animals4 ,living sponges secrete a skeleton which may be composed of chitin1 silica1 or calcium carbonate4 ,these substances are commonly found in the form of spicules--tiny hard parts that are used to help support the soft tissues of the animal4 ,these spicules take on a variety of shapes 7,pl4 #ad7 and are occasionally found as microfossils in some marine sediments4 ,although sponges are not particularly common fossils1 their remains occur in some parts of the ,state4 ,sponges have been collected from ,paleozoic and ,mesozoic formations of north and ,trans-,pecos ,texas1 and their spicules have been reported from well cuttings4 ,phylum ,coelenterata ,the coelenterates are multicelled animals which1 though more complex than the sponges1 are rather primitive animals4 ,the living animal is characterized by a sac-like body cavity1 a definite mouth1 and tentacles which bear stinging cells4 ,some forms1 for example1 the jellyfishes1 have an umbrella-shaped body and are single free-moving organisms4 ,others1 like the colonial corals1 are composed of many individuals living together in a colony4 ,most zoologists and paleontologists recognize three classes of coelenterates3 7#a7 the ,hydrozoa1 containing the small animals known as hydroids1 7#b7 the ,scyphozoa1 which includes the jellyfish1 and 7#c7 the ,anthozoa1 which includes the corals and sea anemones4 ,because of their extreme fragility and lack of hard parts1 hydrozoans and scyphozoans are not commonly found as fossils4 ,they do1 however1 have a long geologic history and may be preserved when unusual conditions of fossilization occur4 ,the anthozoans1 especially the corals1 are by far the most important class geologically1 and these forms have left a very good paleontological record4 ,,class ,,anthozoa4-- ,this class is composed of a group of exclusively marine organisms and includes the corals and sea anemones4 ,the coral animal1 or polyp1 secretes a cup-shaped calcareous 7limy7 exoskeleton4 ,this skeleton1 called a corallite1 is usually divided by radial partitions called septa4 ,the polyp lives in the calyx1 which is the central bowl-shaped depression in the top of the corallite 7fig4 #aa;a74 ,solitary corals form an individual corallite for each polyp1 and because of their shape these may be given such names as 8horn corals0 7,lophophyllidium1 ,pl4 #ae7 or 8button corals0 7,micrabacia1 ,pl4 #af74 ,colonial or compound corals 7,pl4 #ae7 live together in colonies1 which are formed of many individual skeletons attached to each other 7fig4 #aa;b71 and the compound mass of coral skeletons formed in this manner is called a corallum4 ,fossil corals commonly occur in many marine limestones and in places constitute a large portion of the rock4 ,illustration3 ,fig4 #aa4 ,morphology and principal parts of corals4 7a7 ,solitary or 8horn0 coral4 7b7 ,colonial or compound coral4 a ,columella ,septum ,corallite b ,calyx ,septum ,corallum ,the class ,anthozoa has been divided into several subclasses1 but only one1 the ,zoantharia1 is of paleontological importance4 ,subclass ,zoantharia4-- ,most corals and all sea anemones belong to this subclass4 ,zoantharians are either colonial or solitary and1 because most of them possess a hard preservable exoskeleton1 they are the most important group of anthozoans geologically4 ,the various orders of the subclass ,zoantharia are discussed below4 ,order ,rugosa4-- ,these are corals in which the septa are arranged in cycles of four4 ,both solitary and colonial forms occur1 and they are found only in rocks of ,paleozoic age4 ,rugose corals are abundant in many of the ,paleozoic formations of ,texas1 and two of the more typical forms 7,lophophyllidium and ,caninia7 are illustrated in ,plate #ae4 ,members of this order have been placed in the subclass ,tetracoralla of older classifications4 ,order ,scleractinia4-- ,the scleractinians are solitary or colonial corals in which the septa grow in multiples of six1 and they are the most important and abundant of the modern corals4 ,these corals were the dominant reef builders of ,mesozoic and ,cenozoic seas1 and their remains are common in many of the marine formations of the ,state4 ,plate #af illustrates some typical scleractinian corals from the rocks of ,texas4 ,this order has also been referred to as subclass ,hexacoralla1 and its members have been called hexacorals4 ,order ,tabulata4-- ,these are corals that are now extinct but are known from fossils in both ,paleozoic and ,mesozoic rocks4 ,tabulate corals are characterized by horizontal partitions called tabulae1 and septa are absent or poorly developed4 ,the tabulates were the most abundant reef-building corals during ,paleozoic time and are well known as fossils4 ,because of certain similarities with other anthozoans1 some paleontologists have treated the ,tabulata as a distinct subclass rather than as an order of the ,zoantharia4 ,tabulate corals are not uncommon in many of the ,paleozoic rocks of ,texas1 and two of these 7,cladochonus and ,striatopora7 are illustrated in ,plate #ae4 ,phylum ,bryozoa ,illustration3 ,fig4 #ab4 ,two types of bryozoans or 8moss animals40 7a7 ,section of the lacy type bryozoan4 7b7 ,the spiral axis of ,archimedes 7,mississippian74 ,bryozoans are colonial animals that are often referred to as 8sea mats40 ,they have been called this because they are commonly found matted on shells1 rocks1 fossils1 and other objects4 ,the living animal is quite small1 has a tentacle-bearing ridge surrounding the mouth1 and secretes a tiny cup-like exoskeleton composed of calcareous or chitinous material4 ,these little chambers1 known as zooecia 7or autopores71 are seen as small pits on the surface of the bryozoan colony 7,rhombopora1 ,pl4 #ag74 ,the zooecia grow together to form the bryozoan colony1 and some fossil colonies grow to be as much as #b feet across4 ,such colonies may be spiral 7fig4 #ab;b71 branching1 or lace-like 7fig4 #ab;a71 and the latter two types are very common in many of the fossiliferous strata of ,texas4 ,undoubted bryozoan fossils have been recorded in rocks of ,lower ,ordovician age1 but questionable ,cambrian forms have also been reported4 ,bryozoans are abundant in the seas of today1 but only a few forms inhabit fresh waters4 ,illustration3 ,plate #ad ,illustration3 ,,sponge ,,spicules 7,,greatly ,,enlarged7 ,illustration3 ,,paleozoic ,,sponges ,,meandrostia #a ,,heliospongia #a ,,astraeospongium ,,astylospongia ,,receptaculites ,,girtyocoelia #b ,illustration3 ,plate #ae ,,pennsylvanian ,,corals ,,cladochonus #a ,,striatopora #a ,,lophophyllidium ,,proliferum #a ,,michelinia #a ,,caninia #a ,,lophophyllidium ,,radicosum #a ,illustration3 ,plate #af ,illustration3 ,,cretaceous ,,corals ,,cladophyllia #a ,,parasmilia #a ,,pleurocora #a ,illustration3 ,,tertiary ,,corals ,,endopachys #a ,,astrhelia #a ,,flabellum #a ,,micrabacia #b ,,trochosmilia #a ,in ,texas one may expect to find bryozoan remains in the ,pennsylvanian rocks of north-central and ,trans-,pecos ,texas where they are abundant in certain of the marine shales and limestones4 ,bryozoans may also be collected from some ,cretaceous and ,tertiary beds1 but their remains are small and fragmental and they are easily overlooked4 ,bryozoans have also been found matted on the shells of fossil mollusks and other invertebrates4 ,phylum ,brachiopoda ,the brachiopods are a large group of exclusively marine organisms with shells composed of two pieces called valves 7fig4 #ac74 ,these valves are usually composed of calcareous or phosphatic material and enclose and protect the soft parts of the brachiopod animal4 ,the soft parts are composed of muscles1 the mantle 7which secretes the valves71 digestive1 respiration1 reproductive1 and excretory organs1 and the tentacle-bearing lophophore4 ,in adult life the brachiopod is attached to the sea bottom by means of a fleshy stalk called the pedicle 7fig4 #ad71 and this is usually extruded through a hole 7the pedicle foramen7 which is located in the ventral or pedicle valve4 ,the upturned area which is usually present on the pedicle valve is called the beak4 ,the other valve1 known as the dorsal or brachial valve1 is usually the smaller of the two 7fig4 #ac;b74 ,the two valves are opened by means of muscles1 and since death results in relaxation of these muscles1 fossil brachiopods are typically found with valves closed4 ,brachiopods vary greatly in size and shape and exhibit a wide variety of ornamentation1 such as spines1 ribs1 nodes1 and other structures4 ,they are abundant fossils in many of the ,paleozoic rocks of ,texas but are relatively rare in ,mesozoic and ,cenozoic formations4 ,the phylum has been divided into two subclasses1 the ,inarticulata and the ,articulata4 ,this classification is based upon the nature of the hinge-line--the edge of the shell where the two valves articulate4 ,illustration3 ,fig4 #ac4 ,morphology and principal parts of articulate brachiopods4 a ,pedicle foramen ,hinge line b ,pedicle valve ,beak ,brachial valve ,,class ,,inarticulata4-- ,the members of this class are rather primitive and have a long geologic history4 ,these brachiopods have valves which are not provided with hinge teeth1 the valves being held together by muscles1 and a hinge-line is lacking 7fig4 #ad74 ,most inarticulate brachiopods are circular or tongue-like in shape and commonly composed of chitinous and phosphatic material4 ,inarticulate brachiopods range from ,lower ,cambrian to ,recent in age but were never as common as the articulate brachiopods1 which are described below4 ,brachiopods belonging to this class have been recorded from several ,paleozoic formations in ,texas 7,pl4 #ag1 ,lingula1 ,apsotreta1 ,angulotreta74 ,illustration3 ,plate #ag ,illustration3 ,,pennsylvanian ,,bryozoans ,,fistulipora #f ,,polypora #e ,,rhombopora #h ,illustration3 ,,cambrian ,,brachiopods ,,apsotreta #aj ,,lingula #d ,,angulotreta #aj ,illustration3 ,,mississippian ,,brachiopods ,,rhipodomella #a ,,dictyoclostus #a ,,camarotoechia #a ,illustration3 ,fig4 #ad4 ,lingula1 a typical ,recent inarticulate brachiopod showing extended pedicle4 ,pedicle ,valve ,,class ,,articulata4-- ,articulate brachiopods have a well-defined hinge-line 7fig4 #ac;a74 ,one valve has well-developed teeth which articulate with sockets in the opposing valve1 and there is a well-developed muscle system which aids in opening and closing the shell4 ,articulate brachiopods are characterized by calcareous shells which are typically of unequal size and a wide variety of shapes 7,pls4 #ah1 #ai74 ,the class has been divided into several orders which have been established primarily on the nature of the pedicle foramen and the nature of shell growth4 ,articulate brachiopods range from ,lower ,cambrian to ,recent in age and are particularly abundant in certain ,pennsylvanian formations of north-central and ,trans-,pecos ,texas4 ,they are also present in certain other fossiliferous strata of ,paleozoic age but are less abundant and not as well preserved4 ,the only ,cretaceous brachiopod that is found in large numbers is ,kingena wacoensis 7,roemer7 7fig4 #ae71 which is particularly abundant in certain formations in the upper part of the ,comanche series4 ,illustration3 ,fig4 #ae4 ,kingena wacoensis1 a common ,cretaceous brachiopod4 7a7 ,dorsal view4 7b7 ,lateral view4 7c7 ,ventral view4 ,phylum ,mollusca ,the phylum ,mollusca encompasses a large group of aquatic 7water-dwelling7 and terrestrial 7land-dwelling7 invertebrates which includes such familiar forms as the snails1 clams1 oysters1 squids1 and octopuses4 ,most mollusks possess a calcareous shell that serves as an exoskeleton1 and these hard parts are well adapted for preservation as fossils4 ,however1 some mollusks 7the slugs7 have no shells1 and others 7the squids7 have an internal calcareous shell4 ,because of their relative abundance and great variety1 mollusks are particularly useful fossils4 ,moreover1 the remains of certain mollusks1 such as the oysters1 are important rock builders4 ,the phylum ,mollusca has been divided into five classes3 #a4 ,amphineura--the chitons or sea-mice2 shell composed of eight valves or plates2 not a common fossil4 ,ordovician to ,recent4 #b4 ,scaphopoda--the tusk-shells2 shell composed of a single tusk-like valve2 generally not a common fossil but locally abundant in certain ,cenozoic formations4 ,devonian to ,recent4 #c4 ,gastropoda--the snails and slugs2 slugs are without shells1 snails have a single-valved shell which is typically coiled2 common fossils in ,paleozoic1 ,mesozoic1 and ,cenozoic rocks4 ,cambrian to ,recent4 #d4 ,pelecypoda--clams1 mussels1 oysters1 scallops2 shells composed of two valves1 usually1 but not always1 of equal size2 common fossils1 especially in ,mesozoic and ,cenozoic rocks4 ,cambrian to ,recent4 #e4 ,cephalopoda--squids1 octopuses1 the pearly nautilus1 and the ammonoids 7extinct72 shell of one valve1 usually coiled and partitioned by septa2 valuable fossils1 especially in ,paleozoic and ,mesozoic rocks4 8,cambrian1 ,ordovician to ,recent4 ,illustration3 ,plate #ah ,,pennsylvanian ,,brachiopods ,,marginifera #a ,,ambocoelia #a ,,squamularia #a ,,derbya #a ,,mesolobus #a ,,chonetes #a ,,linoproductus #a ,,punctospirifer #a ,,composita ,,subtilita #a ,,neospirifer #a ,illustration3 ,plate #ai ,,pennsylvanian ,,brachiopods ,,juresania #a ,,spirifer ,,rockymontanus #a ,,neospirifer ,,cameratus #a ,of these five classes1 only the ,gastropoda1 ,pelecypoda1 and ,cephalopoda are discussed herein4 ,,class ,,gastropoda4-- ,the typical gastropod has a spirally coiled1 single-valved1 unchambered shell4 ,this shell encloses a soft body possessing a well-defined head with a pair of eyes and one or two pairs of tentacles4 ,most gastropods have gills and live in shallow marine waters1 but some inhabit fresh water4 ,others are land-dwelling forms and breathe by means of lungs4 ,gastropod shells1 both ,recent and fossil1 exhibit a great variety of size1 shape1 and ornamentation4 ,such shells may be cone-shaped1 spirally coiled1 flat1 turreted1 or cylindrical4 ,the shell is commonly wound in a spiral around a central axial pillar 7the columella74 ,the closed pointed end of the shell is called the apex1 and each turn of the shell is called a whorl 7fig4 #af74 ,the last-formed and largest whorl is called the body whorl1 and this whorl contains the aperture--the opening of the shell4 ,the combined whorls exclusive of the body whorl are known as the spire4 ,the inner and outer margins of the aperture are designated the inner lip and the outer lip1 respectively4 ,in some snails the aperture is closed by means of the operculum--a calcareous or horny plate attached to the foot of the animal4 ,this plate effectively seals the aperture when the animal is withdrawn into its shell4 ,some gastropods have shells that are loosely coiled1 and in these forms the columella is absent4 ,if the whorls of such shells are not in contact on the inner surface1 this leaves an open space which is called the umbilicus 7fig4 #af;a74 ,the umbilicus is commonly seen as an opening in the base of the gastropod shell1 but in some forms the umbilical opening may be partially or completely covered by a thick growth of shell called the callus4 ,many gastropods1 particularly those of the ,texas ,cretaceous1 are commonly preserved as internal or external molds4 ,this type of preservation occurs after the death of the animal1 and the decomposition of the soft parts enables the shell to become filled with sediment4 ,this filling later becomes solidified1 and the outer shell may eventually be removed by weathering or solution4 ,this type of internal mold is called a steinkern and normally does not reflect any external shell characteristics 7,pl4 #b74 ,in some of the ,pennsylvanian and ,tertiary formations1 however1 gastropods may be collected with the original shell in an excellent state of preservation4 ,plates #bj-bc illustrate some typical ,paleozoic1 ,mesozoic1 and ,cenozoic gastropods4 ,,class ,,pelecypoda4-- ,the pelecypods possess a shell composed of two calcareous valves 7fig4 #ag7 which enclose the soft parts of the animal4 ,members of this class live exclusively in an aquatic habitat and are most abundant in marine environments4 ,most pelecypods are slow-moving bottom-dwelling forms1 but some1 like the oysters1 are attached4 ,still others1 for example1 the scallop or ,pecten1 are swimmers4 ,the ,pelecypoda include such familiar saltwater forms as the clams and oysters1 as well as the common fresh-water mussel4 ,pelecypods range from ,cambrian to ,recent in age but are more abundant in ,mesozoic and ,cenozoic rocks4 ,the living animal is aquatic1 with well-developed soft parts and a muscular1 commonly hatchet-shaped foot4 ,the soft mantle encloses the body and secretes the shell1 and in some pelecypods part of the mantle is developed into the incurrent and excurrent siphons4 ,the incurrent siphons bring fresh water and food into the mantle cavity1 and waste products are passed out through the excurrent siphons4 ,respiration is by means of gills within the mantle cavity4 ,the typical pelecypod valves are of equal size and form1 but some1 such as the scallops and oysters1 have two valves of unequal size and shape4 ,the valves are hinged and held together by a tough elastic ligament which runs along the dorsal 7top7 side of the shell4 ,in addition to the ligament1 most forms have teeth and sockets which are located along the hinge-line4 ,the teeth in one valve articulate with the sockets in the opposite valve1 and this arrangement gives strength to the hinge4 ,illustration3 ,fig4 #af4 ,morphology and principal parts of gastropod shells4 7a7 ,low-spired form with umbilicus4 7b7 ,section of spirally coiled shell showing columella4 a ,suture ,whorl ,body whorl ,aperture ,umbilicus b ,apex ,spire ,columella ,body whorl ,inner lip ,outer lip ,most of the pelecypod shell is of calcium carbonate1 but the outer layer1 or periostracum1 of each valve is composed of horny material4 ,the inner surface of the shell is lined with a calcareous layer of pearly or porcelaneous material4 ,illustration3 ,plate #bj ,,pennsylvanian ,,gastropods ,,straparolus #a ,,amphiscapha #a ,,worthenia #a ,,trepospira #a ,,bellerophon #a ,,euomphalus #a ,illustration3 ,plate #ba ,illustration3 ,,pennsylvanian ,,gastropods ,,euphemites #a ,,strobeus #a ,,platyceras #a ,illustration3 ,,cretaceous ,,gastropods ,,internal ,,molds ,,gyrodes #a ,,lunatia #a ,,turritella #a ,,cerithium #a ,,tylostoma #a ,,nerinea #a ,illustration3 ,plate #bb ,,tertiary ,,gastropods ,,distorsio #a ,,mesalia #a ,,fusus #a ,,cochlespiropsis #a ,,turritella #a ,,latirus #a ,,conus #a ,,vertagus #a ,,pseudoliva #a ,illustration3 ,plate #bc ,,tertiary ,,gastropods ,,ancilla #a ,,archetectonica #a ,,tuba #a ,,calyptraphorus #a ,,sycostoma #a ,,surcula #a ,,volutolithes #a ,,neverita #a ,,levifusus #a ,the outline of the shell may vary greatly1 but most pelecypods are typically clam-like4 ,however1 certain forms are round1 others are long and narrow1 and some have wing-like structures4 ,most pelecypods have a beak which represents the oldest part of the shell4 ,the beak is commonly located on the anterior 7front7 end of the shell1 and the end of the shell opposite this is designated posterior 7the rear74 ,the hinge and ligament are located dorsally 7along the top71 and the lower margin of the shell where the valves open is called ventral 7fig4 #ag;a74 ,illustration3 ,fig4 #ag4 ,morphology and principal parts of a typical pelecypod shell4 7a7 ,exterior view4 7b7 ,interior view4 a ,dorsal ,beak ,anterior ,posterior ,concentric growth rings ,ventral b ,hinge teeth ,cardinal teeth ,anterior muscle scar ,posterior muscle scar ,mantle line ,the inner surface of the shell has certain markings which1 along with the shell form and dentition 7the nature and arrangement of the teeth and sockets71 are important in classification4 ,muscle scars are present on the inside of most valves2 the anterior muscle scars are located near the front of the shell1 and the posterior muscle scars are situated near the rear of the shell4 ,these scars mark the place of attachment of muscles which were used to close the shell and aid in locomotion4 ,along the ventral margin of some shells there is a line or scar which extends from the anterior muscle scar to the posterior muscle scar4 ,this is known as the mantle line or pallial line and marks the place of attachment of the mantle--a soft membranous layer that enclosed the body of the animal4 ,in some pelecypods the dorsal margin of one valve bears a series of hinge teeth which articulate with a similar set of sockets on the other valve 7fig4 #ag;b74 ,in addition to hinge teeth1 certain species have cardinal teeth which are located below and in front of the hinge teeth4 ,the exterior of most shells is marked by a series of concentric growth lines 7fig4 #ag;a7 which mark points of periodic addition of shell material4 ,the external surface of many shells is also marked by various types of ornamentation1 such as ribs1 nodes1 spines1 and grooves4 ,fossil collectors commonly find only one valve of the pelecypod shell4 ,this is because the shell normally opens when the animal dies1 and the valves may easily become separated4 ,fossil pelecypods are also commonly preserved as external and internal molds1 and these are found in fossiliferous strata of almost all ages4 ,some pelecypods of ,pennsylvanian1 ,mesozoic1 and ,cenozoic age are found with original shell material that appears to have undergone very little change4 ,fossil pelecypods are abundant and varied in ,texas and are found in most of the fossiliferous formations of the ,pennsylvanian1 ,cretaceous1 and ,tertiary systems 7,pls4 #bd-ca74 ,,class ,,cephalopoda4-- ,these are marine mollusks with or without chambered or solid shells which may be internal or external4 ,the living animal possesses a well-developed head with eyes1 horny jaws1 and many tentacles fused with the foot4 ,cephalopods are the most advanced of all mollusks and include the squid1 octopus1 pearly nautilus1 and the extinct ammonoids4 ,members of this class range from ,cambrian to ,recent in age but were much more abundant in ancient seas than they are today4 ,their remains constitute a very useful group of fossils1 particularly in ,paleozoic and ,mesozoic rocks4 ,most paleontologists have divided the ,cephalopoda into three subclasses1 the ,nautiloidea1 ,ammonoidea1 and the ,coleoidea 7known also as subclass ,dibranchiata and subclass ,decapoda72 each of these is discussed below4 ,subclass ,nautiloidea4-- ,the nautiloids are cephalopods with external chambered shells in which the septa 7dividing partitions7 are simple and have smooth edges4 ,this subclass is represented by a single living genus1 ,nautilus1 and a large number of fossil forms4 ,in the living ,nautilus the shell is composed of calcium carbonate and is coiled in a flat spiral 7fig4 #ah74 ,the interior of the shell is divided into a series of chambers by calcareous partitions called septa4 ,the point where each septum joins the inner surface of the shell is known as the suture4 ,these suture lines 7fig4 #ai;a7 are not visible from the outside unless the outer shell has been removed1 but they are visible on the internal molds of many fossil cephalopods and are of great importance in nautiloid and ammonoid classification4 ,nautiloids have very simple smoothly curved suture patterns1 but ammonoids are characterized by more complex and wrinkled sutures 7fig4 #ai;d74 ,although the shell of the only type of living nautiloid is coiled1 many of the early forms had straight cone-shaped shells 7,orthoceras1 ,pl4 #cb71 and these are common in some of the ,pennsylvanian formations of ,texas4 ,fossil coiled nautiloids may be collected in certain of the ,cretaceous and ,tertiary strata of the ,state1 but their remains are not common4 ,cymatoceras 7,pl4 #cb7 is a coiled fossil nautiloid from the ,cretaceous of north ,texas4 ,illustration3 ,plate #bd ,,pennsylvanian ,,pelecypods ,,schizodus #a ,,myalina ,,astartella #a ,,nuculopsis #a ,,allorisma #a ,,nuculana #a ,,yoldia #a ,,pinna ,illustration3 ,plate #be ,,cretaceous ,,pelecypods ,,protocardia #a ,,alectryonia ,,lugubris #a ,,plicatula #a ,,pecten #a ,illustration3 ,plate #bf ,,cretaceous ,,pelecypods ,,gryphaea ,,washitaensis #a ,,gryphaea ,,graysonana #a ,,inoceramus #a ,,trigonia #a ,illustration3 ,plate #bg ,,cretaceous ,,pelecypods ,,exogyra ,,arietina #a ,,exogyra ,,laeviscula #a ,,neithea #a ,,exogyra ,,ponderosa #a ,,exogyra ,,texana #a ,illustration3 ,plate #bh ,,cretaceous ,,pelecypods ,,pachymya ,,ostrea ,,carinata #a ,,ostrea ,,quadriplicata #a ,,pholadomya #a ,illustration3 ,plate #bi ,,tertiary ,,pelecypods ,,lima #a ,,ostrea ,,lisbonensis #a ,,pitar #a ,,venericardia ,,bulla #a ,,pachecoa #b ,,pholadomya #b ,,ostrea ,,sellaeformis #a ,,crassatella #a ,illustration3 ,plate #cj ,,tertiary ,,pelecypods ,,orthoyoldia #a ,,tellina #a ,,vokesula #b ,,nucula #b ,,venericardia ,illustration3 ,plate #ca ,,tertiary ,,pelecypods ,,plicatula #a ,,pecten #a ,,anomia #a ,,glycymeris #b ,,caryocorbula #b ,,barbatia #a ,illustration3 ,fig4 #ah4 ,morphology and principal parts of the pearly nautilus4 7a7 ,exterior view of a ,recent shell4 7b7 ,sectioned view of the same shell to show internal structures4 b ,living chamber ,aperture ,septa ,siphuncle ,protoconch ,chamber ,illustration3 ,fig4 #ai4 ,characteristic features of the various types of cephalopod sutures4 7a7 ,nautiloid type4 7b7 ,goniatite type4 7c7 ,ceratite type4 7d7 ,ammonite type4 ,subclass ,ammonoidea4-- ,the ammonoids are a group of extinct cephalopods which are related to the nautiloids but are characterized by more complex suture patterns4 ,members of this subclass have an external partitioned shell which is straight1 curved1 or spirally coiled 7,pl4 #cc74 ,this group of cephalopods first appeared in ,devonian time1 became extremely abundant and varied during the ,mesozoic1 and was extinct by the end of the ,cretaceous period4 ,most ,paleozoic ammonoids are characterized by a combination curved and angular suture pattern1 and this type of suture pattern is referred to as goniatitic 7fig4 #ai;b74 ,sutures that are curved and crenulated 7marked in places by a series of tooth-like indentations7 are known as ceratitic 7fig4 #ai;c74 ,ceratitic sutures first appeared in the ,mississippian1 became increasingly abundant during the ,triassic but were much less abundant during the ,cretaceous4 ,the ammonitic suture has a very complexly subdivided pattern 7fig4 #ai;d74 ,cephalopods with ammonitic sutures range from ,pennsylvanian to ,cretaceous in age and were the most abundant cephalopods of the ,mesozoic4 ,illustration3 ,plate #cb ,illustration3 ,,pennsylvanian ,,cephalopods ,,phaneroceras #a ,,orthoceras #a ,illustration3 ,,cretaceous ,,cephalopods ,,metoicoceras ,,cymatoceras ,illustration3 ,plate #cc ,,cretaceous ,,cephalopods ,,texanites ,,acanthoceras ,,turrilites ,,dufrenoyia ,,oxytropidoceras ,,baculites ,,belemnite ,ammonoids are locally abundant in many of the fossiliferous rocks of ,texas and are among the more useful ,mesozoic guide fossils4 ,goniatites may be found in the ,pennsylvanian of north-central and ,trans-,pecos ,texas1 and ammonoids with the ceratitic suture pattern can be collected from the ,lower ,cretaceous of many parts of the ,state4 ,cephalopods exhibiting the typical ammonitic suture pattern are abundant in many of the ,cretaceous rocks of ,texas1 and these fossils have contributed much toward an understanding of the ,cretaceous strata of this ,state4 ,subclass ,coleoidea4-- ,these are squid-like cephalopods characterized by an internal shell or no shell at all4 ,included in this group are the squids1 cuttlefish1 octopuses1 and the extinct belemnoids1 but of these only the belemnoids are useful fossils4 ,members of this subclass range from ,mississippian to ,recent in age4 ,order ,belemnoidea4-- ,the belemnoids appear to be the oldest and most primitive of the coleoid cephalopods4 ,their earliest known occurrence is in rocks of ,mississippian age1 and they were particularly abundant during the ,mesozoic4 ,they became extinct at the end of ,cretaceous time but have left considerable evidence of their existence in the ,mesozoic strata of many parts of the world4 ,certain forms1 because of their abundance and relatively short geologic range1 are excellent guide fossils4 ,belemnoids have been found in the ,upper ,cretaceous of ,texas 7,pl4 #cc7 but in general are rare or unknown in most ,texas formations4 ,phylum ,annelida ,members of the phylum ,annelida include the segmented worms such as the common earthworm4 ,annelids are marine1 fresh water1 or terrestrial and have apparently been common through much of geologic time4 ,because of their lack of hard parts1 most of these worms have left little direct fossil evidence of their activities in the geologic past4 ,some annelids secrete straight or coiled calcareous tubes1 and fossil worm tubes of this sort 7fig4 #bj7 are commonly found attached to brachiopods1 mollusks1 and other objects4 ,tubes of this nature have been reported from ,paleozoic1 ,mesozoic1 and ,cenozoic rocks in ,texas4 ,illustration3 ,fig4 #bj4 ,types of typical annelid worms4 7a7 ,serpula 7#a7 7b7 ,hamulus 7#b74 7c7 ,spirobis 7#ae74 ,some annelids have small chitinous jaws and teeth which also may be preserved as fossils4 ,these dental structures are called scolecodonts and are microfossils4 ,phylum ,arthropoda ,the arthropods are one of the more advanced groups of invertebrates1 and they are known from the ,cambrian to the ,recent 7,pl4 #cd74 ,modern representatives of this group include the crabs1 shrimp1 crayfish1 insects1 and spiders4 ,arthropods vary greatly in size and shape and are among the most abundant of all animals4 ,they have become successfully adapted to a wide variety of environments and live on land1 in water1 and in the air4 ,the typical arthropod has a segmented body which is usually covered by a chitinous exoskeleton which1 in some forms1 contains additions of calcium carbonate4 ,they are highly specialized and well-developed animals in which locomotion is by means of paired jointed appendages4 ,although the arthropods are of great importance in nature today1 only a few groups are of importance to the paleontologist4 ,only two of these1 the trilobites and the ostracodes1 are discussed herein4 ,subphylum ,trilobitomorpha ,the members of this subphylum are extinct arthropods which were most abundant during early ,paleozoic time4 ,,class ,,trilobita4-- ,the trilobites are a group of exclusively marine arthropods which derive their name from the typical three-lobed appearance of their bodies 7fig4 #ba;a74 ,the trilobite body is divided into a central or axial lobe and two lateral lobes4 ,the body of the animal was encased in a chitinous exoskeleton4 ,the top part of this exterior covering1 the carapace1 is very thick1 and it is this part of the trilobite that is usually preserved4 ,illustration3 ,plate #cd ,,fossil ,,arthropods ,,fossil ,,insect #a ,,fossil ,,crustaceans ,,enoploclytia #a ,,astacodes ,,notopocorystes #b ,,ostracodes #dj ,illustration3 ,fig4 #ba4 ,morphology and principal parts of trilobites4 ,cephalon ,thorax ,pygidium ,axial lobe ,lateral lobes ,the body is also divided into three parts from front to back4 ,beginning at the front of the animal these divisions are the cephalon or head1 the thorax or abdomen1 and the pygidium or tail 7fig4 #ba;a74 ,the body segments of the thorax were arranged in such a manner as to permit the animal to roll up into a ball1 and many trilobites are found in this position 7fig4 #ba;b74 ,trilobites first appeared in the ,cambrian and were extinct by the end of the ,permian4 ,they occur sparingly in certain of the ,paleozoic rocks of ,texas and when found are likely to be fragmental and in a poor state of preservation4 ,subphylum ,crustacea ,the crustaceans are the crabs1 shrimp1 crayfish1 and ostracodes4 ,although not abundant1 fossil crabs have been described from certain ,cretaceous and ,tertiary formations of the ,state 7,notopocorystes1 ,pl4 #cd74 ,however1 the most useful and abundant crustacean fossils are the members of the class ,ostracoda4 ,,class ,,ostracoda4-- ,the ostracodes are small1 bivalved1 aquatic crustaceans which have the external appearance of small clams 7,pl4 #cd74 ,the remains of these tiny animals are so small that they are best studied under a low-power microscope1 and because of their small size they are particularly useful to the micropaleontologist4 ,fossil ostracodes range from ,ordovician to ,recent in age and have been recorded in the ,paleozoic1 ,mesozoic1 and ,cenozoic rocks of ,texas4 ,their remains are particularly abundant in certain of the ,cretaceous and ,tertiary marine formations of the ,state4 ,phylum ,echinodermata ,the echinoderms are a large group of exclusively marine animals1 most of which exhibit a marked five-fold radial symmetry 7,pls4 #ce1 #cf74 ,living echinoderms have well-developed nervous and digestive systems1 a distinct body cavity1 and are a relatively complex group of organisms4 ,the typical echinoderm has a skeleton composed of numerous calcareous plates which are intricately fitted together and covered by a leathery outer skin 7the integument74 ,the echinoderm body often exhibits a typical star-shaped form1 but some types may be heart-shaped1 biscuit-shaped1 or cucumber-shaped4 ,members of this phylum range from ,cambrian to ,recent in age and are abundant as fossils in many of the marine formations of ,texas4 ,the phylum ,echinodermata has been divided into two subphyla1 the ,pelmatozoa 7those forms that were attached to sea floor by a stem or a stalk7 and the ,eleutherozoa 7the stemless unattached echinoderms74 ,subphylum ,pelmatozoa ,these are echinoderms which are more or less permanently attached to the bottom of the sea by means of a stalk which is composed of slightly movable1 calcareous1 disk-like segments 7fig4 #bc74 ,pelmatozoans range from ,cambrian to ,recent in age1 and their fossilized remains are particularly abundant in ,paleozoic rocks4 ,the subphylum has been divided into several classes1 but only three of these1 the ,cystoidea1 ,blastoidea1 and ,crinoidea1 are discussed here4 ,with the exception of the ,crinoidea1 all of the attached echinoderms are extinct4 ,,class ,,cystoidea4-- ,these are primitive attached echinoderms which were relatively common in early ,paleozoic time4 ,the typical cystoid has a somewhat globular or sac-like calyx 7the main body skeleton7 composed of numerous1 irregularly arranged1 calcareous plates 7fig4 #bb;b74 ,the plates composing the calyx are usually perforated by pores or slits which were probably used in excretion or respiration4 ,the calyx was attached to the sea bottom by a short stem4 ,cystoids range from ,cambrian to ,devonian in age and were especially abundant during ,ordovician and ,silurian time4 ,their remains are rare or absent in the rocks of ,texas4 ,illustration3 ,fig4 #bb4 ,two extinct attached echinoderms4 7a7 ,pentremites 7,mississippian74 7b7 ,caryocrinites 7,silurian74 ,,class ,,blastoidea4-- ,the blastoids are extinct short-stemmed echinoderms with a small1 symmetrical1 bud-like calyx4 ,the blastoid calyx is composed of #ac calcareous plates arranged in a typical five-sided pattern 7fig4 #bb;a74 ,the mouth is located in the center of the calyx and is surrounded by five openings called spiracles4 ,five distinct ambulacral or food grooves radiate outward from the mouth4 ,blastoids range from ,ordovician to ,permian in age and were especially abundant during the ,mississippian period4 ,no blastoids have been reported from any of the rocks of ,texas4 ,,class ,,crinoidea4-- ,the crinoids are commonly called sea-lilies because of their flower-like appearance4 ,the calyx is composed of symmetrically arranged calcareous plates1 and most crinoids have a long stem4 ,other crinoids are free-swimming in the adult stage and are attached only during the earlier phases of their development4 ,the crinoid calyx is typically cup-shaped 7fig4 #bc7 and five grooves radiate out from its center4 ,these grooves continue outward along the complexly segmented arms and are used as channels to convey food to the mouth4 ,illustration3 ,fig4 #bc4 ,typical modern crinoid1 or 8sea lily10 showing principal parts4 ,calyx ,arm ,plate ,stem ,columnal ,cirri ,holdfast 7root7 ,the crinoid stem is attached to the base of the calyx and serves for purposes of support and attachment4 ,this stem consists of a relatively long flexible stalk composed of numerous calcareous disk-shaped segments called columnals 7fig4 #bc2 ,pl4 #ce71 each of which contains a round or star-shaped opening in its center4 ,many crinoids have very long stalks 7some are as much as #ej feet in length71 and when the animal dies the columnals become separated and are scattered about on the ocean floor4 ,many ,paleozoic limestones contain such great numbers of crinoid columnals that they are referred to as crinoidal limestones 7fig4 #h74 ,crinoidal limestones occur in some of the ,mississippian and ,pennsylvanian formations of central ,texas and in the ,pennsylvanian of north-central and ,trans-,pecos ,texas4 ,the stalk is attached to the sea floor or some other object by means of a root system called the holdfast 7fig4 #bc74 ,this structure commonly branches out into the surrounding sediments1 and in this manner the crinoid animal is firmly anchored to the bottom of the sea4 ,crinoids1 like most echinoderms1 are gregarious animals--that is1 they commonly live together in large numbers1 and for this reason great numbers of crinoid remains are commonly found concentrated in relatively small local areas4 ,most fossil crinoids are found as stem fragments because the more fragile calyx and root system are less likely to be preserved4 ,the earliest known crinoids have been found in rocks of ,ordovician age1 and their remains are particularly abundant in ,paleozoic rocks4 ,crinoids are living today but most of them are stemless free-swimming forms called 8feather stars10 much less abundant than their ,paleozoic ancestors4 ,subphylum ,eleutherozoa ,the eleutherozoans are free-swimming1 bottom-dwelling1 echinoderms which have been divided into two classes4 ,the class ,asterozoa 7star-shaped echinoderms7 contains the subclasses ,asteroidea 7the starfishes7 and the ,ophiuroidea 7the brittle stars74 ,although they are known as fossils1 neither of these groups is of paleontological importance4 ,the class ,echinozoa 7echinoderms without laterally directed arm-like extensions7 contains the subclasses ,echinoidea 7the sea urchins and sand dollars7 and ,holothuroidea 7the sea cucumbers74 ,of these two subclasses1 only the ,echinoidea are useful fossils4 ,,class ,,asterozoa4-- ,these are typical star-shaped free-moving echinoderms in which the body is divided into a central disk and radiating arms4 ,subclass ,asteroidea4-- ,this class contains the starfishes which1 although not common fossils1 illustrate well the typical echinoderm characteristics 7,pl4 #ce74 ,fossil starfishes have been found sparingly in certain formations in ,texas1 but well-preserved specimens are quite rare4 ,however1 excellently preserved starfishes have been found in slabs of ,cretaceous limestones from central and north-central ,texas4 ,subclass ,ophiuroidea4-- ,the ophiuroids are echinoderms with a well-defined central disk and five long1 slender1 whip-like arms4 ,they have been called brittle stars because of their ability to shed their arms when they are disturbed4 ,their long1 slender1 snake-like arms have also resulted in their being called serpent stars4 ,ophiuroids range from ,ordovician to ,recent in age1 but because of the delicate nature of their bodies they are seldom found as fossils4 ,ophiuroid remains have been found in certain ,mesozoic and ,cenozoic rocks of ,texas1 but they consist largely of small segments of the arms or body fragments4 ,,class ,,echinozoa4-- ,the echinozoans are a group of unattached echinoderms whose bodies consist of numerous calcareous plates and spines1 but they do not possess the radiating arm-like extensions which characterize the asterozoans4 ,subclass ,echinoidea4-- ,echinoids are free-moving echinoderms with disk-shaped1 heart-shaped1 biscuit-shaped1 or globular exoskeletons 7,pl4 #cf74 ,modern representatives of this group include the familiar sea urchins1 heart urchins1 and the sand dollars4 ,illustration3 ,plate #ce ,,crinoids ,,crinoid ,,calyx ,,crinoid ,,columnals #a ,,holothurian ,,sclerites 7,,greatly ,,enlarged7 ,,cretaceous ,,fossil ,,starfishes ,,pentagonaster #a ,,pentaceros #a ,illustration3 ,plate #cf ,,cretaceous ,,echinoids ,,salenia #a ,,echinoid ,,spines #b ,,echinoid ,,plate #b ,,hemiaster #a ,,holaster #a ,,holectypus #a ,the echinoid test 7exoskeleton7 is composed of many intricately fitting calcareous plates 7,pl4 #cf7 which enclose the animal's soft parts4 ,the exterior of the test is typically covered with large numbers of movable spines 7,pl4 #cf7 which vary greatly in size4 ,these spines are of some aid in locomotion1 support the skeleton of the animal1 and provide a measure of protection from enemies4 ,the oldest known echinoids have been recorded from rocks of ,ordovician age1 but it was not until the ,mesozoic that the group began to flourish4 ,they were especially abundant during the ,cretaceous and have been abundant and varied from that time until the present4 ,echinoids are particularly numerous in many of the ,lower ,cretaceous formations of ,texas where they are commonly found in an excellent state of preservation4 ,heart urchins and biscuit urchins may be found in large numbers in many areas of the ,state1 and especially in areas where there are good exposures of fossiliferous ,lower ,cretaceous rocks4 ,subclass ,holothuroidea4-- ,members of this class1 commonly called sea cucumbers1 have a rather elongate1 sac-like1 cucumber-shaped body and bear little resemblance to other members of the phylum ,echinodermata4 ,the sea cucumbers do not have a well-defined skeleton2 rather the body is supported by many small1 disconnected1 calcareous plates or rods called ossicles or sclerites 7,pl4 #ce74 ,these minute structures are embedded in the leathery skin which covers the body of the sea cucumber and may be preserved as fossils4 ,such remains are locally abundant in certain formations in ,texas1 but because of their small size1 scattered occurrence1 and problems in classification1 this group is of little use to most paleontologists4 ,holothuroid body impressions have been reported from the ,middle ,cambrian1 and sclerites from rocks as old as ,mississippian4 ,phylum ,chordata ,the chordates are the most advanced of all animals and are characterized by the presence of a well-developed nervous system and a body supported by a bony or cartilaginous notochord and_/or spinal column4 ,in the higher chordates 7the vertebrates7 the notochord is normally replaced by bone1 but in the lower chordates 7for example1 the graptolites7 it remains in a cartilaginous condition4 ,the phylum ,chordata contains only two subphyla of paleontological significance4 ,these are the subphylum ,hemichordata1 composed of primitive chordates 7including the graptolites which are important fossils71 and the ,vertebrata1 which includes all animals with backbones4 ,subphylum ,hemichordata ,the hemichordates are characterized by a well-defined notochord which runs the length of the body1 but they do not possess a true backbone4 ,only one class1 the ,graptolithina1 is of paleontological importance4 ,,class ,,graptolithina4-- ,the graptolites are a group of extinct colonial animals which were very abundant during early ,paleozoic time4 ,they are characterized by a chitinous exoskeleton consisting of rows of cups or tubes which housed the living animal4 ,these cups are attached to single or branching stalks 7fig4 #bd7 which in some forms were attached to sea weeds1 rocks1 or other foreign objects where they led a fixed existence4 ,the stalks of the unattached graptolites grew on floats 7fig4 #bd;a7 and these floating forms attained wide geographic distribution4 ,it is also possible that some of the attached forms were fixed to floating objects1 such as sea weed1 and thus were distributed in this manner4 ,previous classifications have recognized the graptolites as members of the phylum ,coelenterata4 ,as coelenterates they were assigned1 at various times1 to the classes ,hydrozoa1 ,scyphozoa1 and ,graptozoa4 ,in addition1 they were also classified as bryozoans by certain of the early paleontologists4 ,this publication1 in keeping with recent changes in taxonomy1 considers graptolites to be an extinct group of hemichordates4 ,this classification is based upon research in which uncompressed graptolites were etched out of chert and studied in great detail4 ,information derived from these relatively undistorted specimens indicates a much higher degree of body organization than was previously suspected1 and as a result of these studies most paleontologists now consider graptolites to be some form of primitive chordate4 ,illustration3 ,fig4 #bd4 ,graptolites4 7a7 ,diplograptus 7#b74 7b7 ,dendrograptus 7#c74 7c7 ,phyllograptus 7#b74 ,the chitinous graptolite exoskeleton is commonly preserved as a flattened carbon residue2 their remains may be locally abundant along the bedding planes of certain black or dark gray shales4 ,graptolites are known from rocks that range from ,cambrian to ,mississippian in age1 and they are among the most important guide fossils for ,ordovician and ,silurian rocks4 ,graptolites have been reported from ,cambrian rocks in central ,texas and from the ,ordovician of west ,texas 7fig4 #bd74 ,the most abundant of these occur in certain ,ordovician rocks in the ,trans-,pecos area where they are common fossils in certain formations4 ,subphylum ,vertebrata ,the vertebrates are the most advanced of all chordates4 ,they are characterized by a skull and a bony or cartilaginous internal skeleton1 with a vertebral column of bone or cartilage4 ,this subphylum is commonly divided into two superclasses1 the ,pisces 7the fishes and their relatives7 and the ,tetrapoda 7the four-footed animals74 ,as mentioned earlier1 most amateur collectors collect very few vertebrate remains1 and for this reason this group is not discussed in detail4 ,however1 the more important vertebrate classes are briefly reviewed to enable the reader to have some understanding of this important group of animals4 ,this part of the handbook will also serve as an introduction to some of the interesting and unusual1 but now extinct1 animals that have inhabited ,texas in the geologic past4 ,among these animals are giant fishes1 primitive amphibians1 and many different types of dinosaurs4 ,included also are such unusual mammals as the giant ground sloths1 saber-tooth cats1 mammoths1 and mastodons1 all of which are now extinct4 ,the remains of these1 and many other interesting extinct vertebrates1 may be seen in the geological collections of the ,texas ,memorial ,museum at ,austin4 ,many of these displays are accompanied by drawings which depict the scientific restoration of the animal's soft parts and show how the animal may have appeared in life4 ,superclass ,pisces ,the members of this superclass are commonly called fishes and are the simplest and most numerous of all vertebrates4 ,they are aquatic1 free-moving1 cold-blooded 7their blood maintains the temperature of the surrounding water71 and breathe primarily by means of gills4 ,however1 some forms 7the lungfishes7 breathe by means of a lung developed from the air-bladder4 ,the most recent fish classification recognizes four major classes1 the ,agnatha 7primitive jawless fishes71 the ,placodermi 7armored fishes with primitive jaws71 the ,chondrichthyes 7sharks and related forms with cartilaginous internal skeletons71 and the ,osteichthyes 7true bony fishes74 ,,class ,,agnatha4-- ,fishes belonging to this class are primitive1 jawless1 and represented by the living lampreys and hagfishes4 ,the first agnathans appeared in the ,ordovician and were armored by a bony covering on the front part of their bodies4 ,these primitive fishes1 called ostracoderms1 are the earliest recorded fishes and1 in addition1 appear to be the first known vertebrate animals4 ,the ostracoderms first appeared in late ,ordovician time1 increased in numbers in the ,silurian1 and were extinct by the end of the ,devonian4 ,,class ,,placodermi4-- ,these are primitive jaw-bearing fishes1 the majority of which were heavily armored 7,pl4 #cg74 ,the placoderms were shark-like in appearance1 and some of them grew to be as much as #cj feet in length4 ,members of this class appeared first in the ,devonian and lasted into the ,permian1 at which time they became extinct4 ,placoderms are rare in ,texas1 but the fragmentary remains of these primitive fishes have been found in ,devonian rocks in central ,texas4 ,,class ,,chondrichthyes4-- ,this class includes such modern forms as the sharks1 rays1 and skates4 ,they are characterized by skeletons which are composed of cartilage and are very abundant in the marine waters of today4 ,the earliest known representatives of this class are reported from rocks of ,devonian age1 and they have been relatively common up to the present time4 ,shark teeth 7,pl4 #cg7 can be found in ,texas in ,pennsylvanian1 ,permian1 ,cretaceous1 ,paleocene1 ,eocene1 and ,miocene rocks4 ,these are probably the most common vertebrate fossils to be found in ,texas and are usually found in thin-bedded marine limestones or clays4 ,,class ,,osteichthyes4-- ,the ,osteichthyes includes the true bony fishes1 which are the most highly developed and abundant of all fishes4 ,they possess an internal bony skeleton1 well-developed jaws1 an air-bladder1 and1 typically1 an external covering of overlapping scales4 ,included in this class are a primitive group of fishes called crossopterygians4 ,these were very abundant in the ,devonian and are believed to be the ancestors of the amphibians4 ,the modern lungfishes also belong to the class ,osteichthyes1 and these primitive fishes1 which are now found only in ,australia1 ,south ,america1 and ,africa1 breathe by means of gills and lungs which have been developed from the air-bladder4 ,although not abundant as fossils1 the remains of these specialized fishes have added much to present knowledge concerning the development of certain of the higher vertebrates4 ,the remains of bony fishes have been collected at many localities in ,texas1 and fossils of this type have been found primarily in rocks of ,cretaceous age but have been reported from other rocks as well4 ,fish fossils are more commonly found in the form of teeth 7,pl4 #cg71 vertebrae1 scales1 and an occasional well-preserved skeleton4 ,illustration3 ,plate #cg ,illustration3 ,,shark ,,teeth #a ,illustration3 ,,conodonts 7,,greatly ,,enlarged7 ,illustration3 ,,primitive ,,armored ,,fish ,,placoderm 7,,devonian7 ,conodonts 7,pl4 #cg7 are small1 amber-colored1 tooth-like fossils which are believed to represent the teeth of some type of extinct fish4 ,although geologists do not know a great deal about the origin of these strange fossils they are of value in micropaleontology4 ,conodonts have been reported from several ,paleozoic formations in ,texas and are useful guide fossils in some areas4 ,superclass ,tetrapoda ,the tetrapods are the most advanced chordates and are typified by the presence of lungs1 a three- or four-chambered heart1 and paired appendages4 ,included here are the classes ,amphibia 7frogs1 toads1 and salamanders71 ,reptilia 7lizards1 snakes1 turtles1 and the extinct dinosaurs71 ,aves 7birds71 and ,mammalia 7including the mammals1 such as men1 dogs1 whales1 etc474 ,,class ,,amphibia4-- ,the amphibians were the earliest developed four-legged animals and are represented by such living forms as the toads1 frogs1 and salamanders4 ,amphibians are cold-blooded animals that primarily breathe by lungs and spend most of their life on land1 but during their early stages of development they live in the water where they breathe by means of gills4 ,the amphibians apparently developed from the crossopterygian fishes during late ,devonian time and were relatively abundant in the ,pennsylvanian1 ,permian1 and ,triassic4 ,amphibian remains in ,texas are confined largely to lower ,paleozoic and upper ,mesozoic rocks4 ,numerous interesting and important discoveries of fossil amphibians have been made in north and west ,texas where their remains 7,pl4 #dj7 have been collected in association with early types of reptiles4 ,the areas where ,permian red beds are exposed in ,archer and ,baylor counties and where ,triassic red beds are exposed from ,big ,spring north along the edge of the ,high ,plains have furnished most of these specimens4 ,,class ,,reptilia4-- ,the reptiles have become adapted to permanent life on land and need not rely on an aquatic environment4 ,they are cold-blooded and are normally characterized by a scaly skin4 ,reptiles have been much more abundant in the past than they are today1 and they assumed many different shapes and sizes in the geologic past4 ,modern classifications recognize a large number of reptilian groups1 but only the more important of these are briefly reviewed here4 ,cotylosaurs4-- ,these were a group of primitive reptiles which1 although retaining some amphibian characteristics1 became adapted to an exclusively land-dwelling existence4 ,the cotylosaurs lived during the ,pennsylvanian and ,permian and apparently became extinct sometime during the late ,permian4 ,cotylosaurs 7,pl4 #dj7 are well known from the ,permian of north ,texas4 ,turtles4-- ,these are reptiles in which the body is more or less completely enclosed by bony plates4 ,this group is first known as fossils from late ,triassic rocks of ,europe1 and modern representatives of the group include the turtles and tortoises4 ,fragmentary remains of turtle shells are among the most common vertebrate fossils found in the ,tertiary4 ,some of the late ,tertiary land tortoises were #c to #d feet long4 ,the earliest known turtles in ,texas have been found in ,cretaceous rocks4 ,pelycosaurs4-- ,the pelycosaurs were a group of late ,paleozoic reptiles some of which were characterized by the presence of a tall fin on their back 7,pl4 #dj74 ,the fossils of these unusual creatures are well known from the ,permian red beds of north-central ,texas4 ,therapsids4-- ,the therapsids were a mammal-like group of reptiles which were well developed for a terrestrial existence4 ,although the remains of these primitive reptiles are not particularly important fossils1 study of the therapsids has provided much valuable information about the origin of the mammals4 ,members of this group appeared first in the middle ,permian and persisted until the middle ,jurassic1 but therapsid remains have not been reported from ,texas4 ,illustration3 ,plate #ch ,comparison of the dinosaurs4 ,reproduced with permission of ,dr4 ,j4 ,w4 ,dixon1 ,jr41 and ,geology ,department1 ,baylor ,university1 ,waco1 ,texas4 ,,dinosaur ,,saurischians ,,ornithischians ,,stocks ,,dinosaur ,,theropod ,,sauropod ,,ornithopod ,,stegosaur ,,ceratopsian ,,ankylosaur ,,types ,,posture ,,bipedal ,,quadrupedal ,,bipedal ,,and ,,quadrupedal ,,quadrupedal ,,quadrupedal ,,quadrupedal ,,armor ,,unarmored ,,except ,,unarmored ,,unarmored 7,,speed ,,bony ,,plates ,,horns1 ,,bony ,,knobs ,,and ,,spikes ,,for ,,huge ,,sharp ,,was ,,chief ,,along ,,back1 ,,plate ,,over ,,neck ,,over ,,dorsal ,,area1 ,,teeth ,,defense7 ,,spiked-,,tail ,,club-,,like ,,tail ,,diet ,,carnivorous ,,herbivorous ,,herbivorous ,,herbivorous ,,herbivorous ,,herbivorous ,,other ,,large ,,head ,,with ,,huge ,,body1 ,,long ,,slender-,,build1 ,,short ,,neck1 ,,short ,,neck1 8,,armadillo-,,like0 ,,descriptive ,,powerful ,,jaw1 ,,neck ,,and ,,tail1 8,,duck-,,billed0 ,,long ,,tail1 ,,stocky ,,build ,,appearance ,,remarks ,,greatly ,,reduced ,,small ,,head ,,small ,,head ,,fore-,,limbs ,,examples ,,ceratosaurus-,j ,,brachiosaurus-,j ,,parasaurolophus-,k ,,stegosaurus-,j ,,styracosaurus-,k ,,paleoscincus-,k 7,,and ,,age7 ,,allosaurus-,j ,,diplodocus-,j ,,corythosaurus-,k ,,protoceratops-,k ,,ankylosaurus-,k ,j-,,jurassic ,,tyrannosaurus-,k ,,brontosaurus-,j ,,trachodon-,k ,,triceratops-,k ,k-,,cretaceous ,illustration ,illustration ,illustration ,illustration ,illustration ,illustration ,,scale ,,in ,,feet #aj #aj #e #e #e #e ,illustration3 ,plate #ci ,comparison of ,mesozoic flying and swimming reptiles4 ,reproduced with permission of ,dr4 ,j4 ,w4 ,dixon1 ,jr41 and ,geology ,department1 ,baylor ,university1 ,waco1 ,texas4 ,illustration3 ,,flying ,,reptiles--,,pterosaurs ,,group ,,age ,,teeth ,,tail ,,head ,,size ,,example ,,rhamphorhynchoids ,,jurassic ,,well ,,long ,,tail ,,without ,,small ,illustration ,,developed ,,with ,,crest ,,maximum ,,rhamphorhynchus ,,flattened ,,wingspan ,,rudder ,,at ,,of #b ,,feet ,,end ,,pterodactyloids ,,jurassic ,,jaw ,,partly ,,short ,,or ,,with ,,small ,,from ,,size ,illustration ,,and ,,or ,,no ,,tail ,,or ,,large ,,of ,,pteranodon-,k ,,cretaceous ,,completely ,,crest ,,sparrow ,,toothless1 ,,to ,,giants ,,horney ,,beak ,,with ,,span ,,of #be ,illustration3 ,,mesozoic ,,swimming ,,reptiles ,,group ,,age ,,description ,,size ,,habitat ,,example ,,ichthyosaur ,,triassic ,,fish-,,like ,,body1 ,,average ,,marine ,illustration ,,to ,,head ,,long ,,and ,,length ,,ichthyosaurus-,j ,,cretaceous ,,pointed1 ,,no #g ,,distinct ,,neck ,,maximum ,,length #dc ,,mosasaur ,,cretaceous ,,lizard-,,like ,,average ,,marine ,illustration ,,body1 ,,flattened ,,length ,,pylosaurus ,,tail1 #ae-bj ,,double-,,jointed ,,maximum ,,jaw1 ,,recurved ,,length ,,teeth #ej ,,plesiosaur ,,triassic ,,long ,,neck ,,and ,,maximum ,,marine ,illustration ,,to ,,small ,,head ,,or ,,length ,,elasmosaurus-,k ,,cretaceous ,,long ,,head ,,and #ej ,,trinacromerum-,k ,,short ,,neck1 ,,powerful ,,flippers ,,chelonia ,,triassic ,,shaped ,,like ,,maximum ,,marine1 ,illustration 7,,turtles7 ,,to ,,present ,,modern ,,turtles1 ,,size ,,streams1 ,,archelon-,k ,,body ,,covered #aa #ab ,,and ,,with ,,bony ,,plates ,,terrestrial ,,phytosaur ,,triassic ,,crocodile-,,like ,,maximum ,,streams ,illustration ,,body1 ,,nostrils ,,length ,,and ,,swamps ,,rutiodon ,,on ,a 8,,hump0 #be ,,almost ,,between ,,the ,,eyes ,illustration3 ,plate #dj ,,pelycosaur _/ ,,dimetrodon ,,primitive ,,amphibian _/ ,,eryops ,,cotylosaur ,,seymouria ,illustration3 ,plate #da ,,swimming ,,reptiles ,,ichthyosaur _/ ,,mosasaur _/ ,,plesiosaur _/ ,illustration3 ,plate #db ,illustration3 ,,crocodile-,,like ,,reptile _/ ,,phytosaur ,illustration3 ,,flying ,,dinosaurs ,,rhamphorhynchus ,,pteranodon _/ ,ichthyosaurs4-- ,these were extinct1 short-necked1 marine reptiles that were fish-like in appearance4 ,ichthyosaurs resemble the modern dolphins1 and some of them attained lengths of #be to #dj feet 7,pl4 #da71 though the average was much less4 ,the group is known from rocks ranging from middle ,triassic to late ,cretaceous in age4 ,mosasaurs4-- ,the mosasaurs are another group of extinct marine lizards which lived in ,cretaceous seas4 ,some of these great reptiles grew to be as much as #ej feet long1 and their great gaping jaws were filled with many sharp recurved teeth 7,pl4 #da74 ,mosasaurs were present in the great ,cretaceous seas which covered many parts of ,texas1 and their remains have been reported from both north and central ,texas4 ,one such skeleton was found near ,austin1 and its skull is on display in the ,texas ,memorial ,museum4 ,plesiosaurs4-- ,the plesiosaurs were marine reptiles which were characterized by a broad turtle-like body1 paddle-like flippers1 and a long neck and tail 7,pl4 #da74 ,these reptiles were not as streamlined or well equipped for swimming as the ichthyosaurs or mosasaurs1 but the long serpent-like neck was probably very useful in helping the reptile catch fish and other small animals for food4 ,plesiosaur remains range from middle ,triassic to late ,cretaceous in age1 and they have been found in ,cretaceous rocks in ,texas4 ,a short-necked plesiosaur which was collected from ,upper ,cretaceous rocks near ,waco is on display in the ,strecker ,museum at ,baylor ,university in ,waco4 ,phytosaurs4-- ,the phytosaurs were a group of crocodile-like reptiles which ranged from #f to #be feet in length 7,pl4 #db74 ,they resembled the crocodiles both in appearance and in their mode of life1 but this similarity is only superficial1 and the phytosaurs and crocodiles are two distinct groups of reptiles4 ,the phytosaurs are exclusively ,triassic in age and their remains have been collected from ,triassic rocks along the eastern margin of the ,high ,plains of ,texas4 ,crocodiles and alligators4-- ,these reptiles adapted themselves to the same type habitat that was occupied by the phytosaurs1 which preceded them4 ,crocodiles and alligators were much larger and more abundant during ,cretaceous and ,cenozoic time than they are today2 the crocodiles first appeared in the ,cretaceous and the alligators in the ,tertiary4 ,the remains of both crocodiles and alligators have been found in ,texas1 and one such crocodile 7,phobosuchus7 represents the remains of the largest crocodile yet discovered 7,pl4 #dc74 ,this specimen probably had an overall length of #dj to #ej feet1 and its massive skull was #f feet long and possessed exceptionally strong jaws4 ,the remains of this great beast were collected from exposures of ,upper ,cretaceous rocks along the ,rio ,grande in ,trans-,pecos ,texas4 ,pterosaurs4-- ,these were ,mesozoic reptiles with bat-like wings supported by arms and long thin 8fingers0 7,pl4 #db74 ,the pterosaurs were well adapted to life in the air1 and their light-weight bodies and wide skin-covered wings enabled them to soar or glide for great distances4 ,the earliest known pterosaurs were found in lower ,triassic rocks1 and the group became extinct by the end of the ,cretaceous4 ,during this time certain of these creatures attained a wingspread of as much as #bg feet1 but their bodies were small and light4 ,dinosaurs4-- ,the collective term 8dinosaurs0 7meaning terrible lizards7 has been given to that distinctive group of reptiles prominent in ,mesozoic life for some #adj million years4 ,in size1 the dinosaurs ranged from as little as #a foot to as much as #he feet in length and from a few pounds to perhaps #de tons in weight4 ,some were carnivorous 7meat-eaters7 but the majority were herbivorous 7plant-eaters74 ,some were bipedal 7walked on their hind-legs7 while others were quadrupedal 7walked on all fours71 and although most of the dinosaurs were terrestrial in habitat1 aquatic and semi-aquatic forms were also present4 ,according to the structure of their hip bones1 the dinosaurs have been divided into two great orders4 ,these are the ,saurischia 7forms with lizard-like pelvic girdle7 and the ,ornithischia 7dinosaurs with a bird-like pelvic girdle74 ,illustration3 ,plate #dc ,dr4 ,brown1 ,r4 ,t4 ,bird1 and ,dr4 ,schaikjer with the skull of ,phobosuchus1 an extinct crocodile from the ,cretaceous of ,trans-,pecos ,texas4 ,photograph courtesy of the ,american ,museum of ,natural ,history4 ,order ,saurischia4-- ,dinosaurs belonging to this order were particularly abundant during the ,jurassic and are characterized by hip bones that are similar to those of modern lizards4 ,these dinosaurs were first discovered in rocks of ,triassic age and did not become extinct until the end of the ,cretaceous4 ,the lizard-hipped reptiles are divided into two rather specialized groups of dinosaurs3 the theropods 7carnivorous bipedal dinosaurs that varied greatly in size7 and the sauropods 7herbivorous1 quadrupedal1 semi-aquatic1 usually gigantic dinosaurs74 ,,suborder ,,theropoda4-- ,this type of saurischian dinosaur walked on bird-like hind limbs1 and they were exclusively meat-eating forms1 such as ,allosaurus 7,pl4 #dd7 of ,jurassic age4 ,some theropods were exceptionally large and were undoubtedly vicious beasts of prey4 ,this assumption is borne out by such anatomical features as the small front limbs with long sharp claws for holding and tearing flesh1 and the large strong jaws which were armed with numerous1 sharp1 dagger-like teeth4 ,the largest of all known theropods was ,tyrannosaurus rex which1 when standing on his hind limbs1 was almost #bj feet tall4 ,some individuals were as much as #ej feet long1 and ,tyrannosaurus is believed to have been among the most vicious animals to ever inhabit our earth4 ,a cast of the skull of one of these great beasts is on display in the ,texas ,memorial ,museum at ,austin1 and a ,tyrannosaurus tooth has been found in the ,big ,bend ,national ,park in ,trans-,pecos ,texas4 ,,suborder ,,sauropoda4-- ,the sauropods were the largest of all dinosaurs1 and some attained a length of #he feet and probably weighed #dj to #ej tons 7,brontosaurus1 ,pl4 #dd74 ,they were primarily herbivorous dinosaurs which had become adapted to an aquatic or semi-aquatic type of existence and probably inhabited lakes1 rivers1 and swamps4 ,the tracks of sauropod dinosaurs have been collected from ,lower ,cretaceous rocks in central ,texas 7,pl4 #d7 and ,upper ,cretaceous beds in ,big ,bend ,national ,park in ,trans-,pecos ,texas4 ,order ,ornithischia4-- ,the ornithischian1 or bird-hipped dinosaurs1 were herbivorous reptiles which were quite varied in form and size and appear to have been more highly developed than the saurischians4 ,this order includes the duck-billed dinosaurs 7ornithopods71 the plate-bearing dinosaurs 7stegosaurs71 the armored dinosaurs 7ankylosaurs71 and the horned dinosaurs 7ceratopsians74 ,ornithischian tracks are known from ,cretaceous rocks in central and ,trans-,pecos ,texas4 ,,suborder ,,ornithopoda4-- ,these unusual dinosaurs were predominantly bipedal1 semi-aquatic1 and some 7like the duck-billed dinosaurs7 were highly specialized 7,trachodon1 ,pl4 #de74 ,,suborder ,,stegosauria4-- ,the stegosaurs were herbivorous1 quadrupedal ornithischians with large projecting plates down the back and heavy spikes on their tails4 ,the ,jurassic dinosaur ,stegosaurus 7,pl4 #de7 is most typical of the plate-bearing forms4 ,this creature weighed about #aj tons1 was some #cj feet long1 and stood about #aj feet tall at the hips4 ,stegosaurus is characterized by a double row of large1 heavy1 pointed plates which run along the animal's back4 ,these plates begin at the back of the skull and stop near the end of the tail4 ,the tail was also equipped with four or more long curved spikes which were probably used as a means of defense4 ,the animal had a very small skull which housed a brain that was about the size of a walnut1 and it is assumed that these1 and all other dinosaurs1 were of very limited intelligence4 ,stegosaurus remains have not been discovered in ,texas1 but these1 like certain other of the extinct vertebrates1 are mentioned because of their interesting and unusual form4 ,,suborder ,,ankylosauria4-- ,the ankylosaurs were four-footed1 herbivorous1 ,cretaceous dinosaurs which had relatively flat bodies4 ,the skull and back of the animal were protected by bony armor1 and the club-like tail was armed with spikes4 ,paleoscincus 7,pl4 #de71 a typical ankylosaur1 had large spines projecting from along the sides of the body and tail4 ,the armored spiked back and the heavy club-like tail probably provided ,paleoscincus with much-needed protection from the vicious meat-eating dinosaurs of ,cretaceous time4 ,illustration3 ,plate #dd ,,saurischian ,,dinosaurs ,,allosaurus _/ ,,brontosaurus _/ ,illustration3 ,plate #de ,,ornithischian ,,dinosaurs ,,stegosaurus _/ ,,trachodon _/ ,,paleoscincus _/ ,,triceratops _/ ,,suborder ,,ceratopsia4-- ,the ceratopsians1 or horned dinosaurs1 are another group of dinosaurs that are known only from rocks of ,cretaceous age4 ,these plant-eating dinosaurs possessed beak-like jaws1 a bony neck frill which extended back from the skull1 and one or more horns4 ,triceratops 7,pl4 #de7 is the largest of the horned dinosaurs 7some forms were as much as #cj feet long71 and the skull measured #h feet from the tip of the parrot-like beak to the back of the neck shield4 ,,class ,,aves4-- ,because of the fragile nature of their bodies1 birds are seldom found as fossils4 ,in spite of this1 however1 some interesting and important fossil bird remains have been discovered4 ,the oldest known bird was found in ,upper ,jurassic rocks exposed in ,germany4 ,this primitive bird1 named ,archaeopteryx1 is little more than a reptile with feathers4 ,archaeopteryx was a pigeon-sized creature which had scales as well as feathers1 a lizard-like tail1 a toothed beak1 and other definitely reptilian characteristics4 ,during late ,cretaceous time the birds underwent changes that resulted in forms similar to those that are living today1 and most of the present-day birds had developed by the end of the ,tertiary4 ,although not commonly found1 fossil birds have been recorded from certain of the ,cenozoic rocks of ,texas4 ,,class ,,mammalia4-- ,the mammals are animals that are born alive and fed with milk from the mother's breast4 ,they are warm-blooded1 air-breathing1 have a protective covering of hair1 and are the most advanced of all vertebrates4 ,the foregoing features are the more typical mammalian characteristics1 but exceptions to these are found in certain mammals4 ,mammals first appeared in the ,jurassic and were probably derived from some form of mammal-like reptile4 ,although rare during the ,mesozoic1 mammals underwent rapid development and expansion during the ,cenozoic1 and during this era certain types of mammals became extremely large and assumed many bizarre shapes4 ,the majority of these unusual forms lived but a short time but are well known from their fossils1 and the remains of some of these animals which inhabited ,texas during the ,cenozoic may be seen in the ,texas ,memorial ,museum at ,austin4 ,recent mammalian classification recognizes several subclasses and numerous orders and suborders1 but the treatment of the mammals in a publication of this nature must of necessity be somewhat brief and no attempt at detailed classification is made4 ,subclass ,allotheria4-- ,the allotherians first appeared during the ,jurassic and underwent considerable development in the late ,cretaceous and early ,tertiary4 ,included in this subclass are the multituberculates which are a group of small rodent-like animals that were probably the earliest of the herbivorous mammals4 ,these animals were probably never very numerous1 and they became extinct during the early part of ,eocene time4 ,subclass ,theria4-- ,members of this subclass are first known from rocks of ,jurassic age1 and they constitute the largest group of mammals that are living today4 ,therians undergo considerable development before they are born and at birth typically resemble the fully developed animal4 ,this subclass has been divided into several orders but only the more important ones are discussed here4 ,order ,edentata4-- ,the edentates are a rather primitive group of mammals which are represented by such living forms as the anteaters1 tree sloths1 and armadillos4 ,members of this group were common in the southern part of the ,united ,states in ,pleistocene and ,pliocene time1 and fossil edentates have been reported from rocks of this age in ,texas4 ,one such form was ,mylodon 7,pl4 #df71 one of the extinct giant ground sloths4 ,these huge sloths were quite heavy and some of them stood as much as #ae feet tall2 these great creatures were the forerunners of the modern tree sloths of ,south ,america4 ,the mounted skeleton of one of these giant ground sloths is displayed in the ,texas ,memorial ,museum4 ,illustration3 ,plate #df ,,cenozoic ,,mammals ,,entelodont _/ ,,glyptodon _/ ,,mylodon _/ ,another interesting representative of this order was the glyptodont4 ,these peculiar mammals1 which were ancestral to the present-day armadillos1 developed at about the same time as the ground sloths4 ,glyptodon 7,pl4 #df71 a typical glyptodont that has been reported from the ,pleistocene of ,texas1 is quite characteristic of this group4 ,this armadillo-like beast had a solid turtle-like shell that in some forms was as much as #d feet high4 ,from the front of the bone capped head to the tip of its tail1 a large individual might be as much as #ae feet long4 ,the thick heavy tail was protected by a series of bony rings1 and in some species the end of the tail was developed into a bony heavily spiked club4 ,the carapace 7hard outer shell7 of a large glyptodont is mounted at the ,texas ,memorial ,museum4 ,order ,carnivora4-- ,animals belonging to this order are called carnivores and are characterized by clawed feet and by teeth which are adapted for tearing and cutting flesh4 ,the carnivores1 or meat-eaters1 were first represented by an ancient group of animals called creodonts1 and this short-lived group first appeared in the ,paleocene and were extinct by the end of the ,eocene4 ,they ranged from the size of a weazel to that of a large bear1 and their claws were sharp and well developed4 ,their teeth1 however1 were not as specialized as those of modern carnivores1 and the creodont brain was relatively small4 ,it is assumed that these animals had a very low order of intelligence when compared to the more advanced carnivores of today4 ,these early meat-eaters were followed by more specialized carnivores which developed throughout ,cenozoic time4 ,some examples of these are the saber-tooth cat ,dinobastis 7,pl4 #dg7 and the dire wolf ,canis diris 7,pl4 #dg71 both of which have been reported from the ,texas ,pleistocene4 ,some remains of these unusual forms1 representing the cat and dog families1 are on display at the ,texas ,memorial ,museum4 ,order ,pantodonta4-- ,pantodonts1 known also as amblypods1 were primitive1 hoofed1 herbivorous animals4 ,they were distinguished by a heavy skeleton1 short stout limbs1 and blunt spreading feet4 ,the pantodonts appeared first during ,paleocene time and had become extinct by the end of the ,oligocene4 ,order ,dinocerata4-- ,the members of this order are an extinct group of gigantic mammals commonly called uintatheres4 ,uintatherium 7,pl4 #dh71 which is typical of the group1 had three pairs of blunt horns1 and the males had dagger-like upper tusks4 ,some of the uintatheres were as large as a small elephant and stood as much as #g feet tall at the shoulders4 ,the size of the brain in relation to the size of the body suggests that these animals were not as intelligent as most mammals4 ,uintatheres are known from rocks ranging from ,paleocene to ,eocene in age4 ,uintathere remains have been reported from ,big ,bend ,national ,park in ,trans-,pecos ,texas4 ,order ,proboscidea4-- ,the earliest proboscideans1 the elephants and their relatives1 first appeared in the late ,eocene of ,africa and were about the size of a small modern elephant but had larger heads and shorter trunks4 ,proboscidean development is marked by an increase in size1 change in skull and tooth structure1 and elongation of the trunk4 ,two well-known fossil proboscideans are the mammoth and the mastodon1 both of which inhabited ,texas during ,pleistocene time4 ,the mastodons resembled the elephants1 but the structure of their teeth was quite different 7fig4 #be74 ,moreover1 the mastodon skull was lower than that of the elephant and the tusks were exceptionally large--some reaching a length of #i feet4 ,illustration3 ,plate #dg ,,cenozoic ,,mammals ,,dinobastis _/ ,,canis ,,dirus _/ ,,hyracotherium _/ ,,pliohippus _/ ,there were several types of mammoths1 and the woolly mammoth is probably the best known4 ,this animal lived until the end of the ,pleistocene and1 like the woolly rhinoceros discussed below1 is known from ancient cave paintings and frozen remains4 ,information gathered from these sources indicates that this great beast had a long coat of black hair with a woolly undercoat 7,pl4 #di74 ,illustration3 ,fig4 #be4 ,sketches of ,pleistocene 7a7 mastodon tooth 77 and 7b7 mammoth tooth 774 ,during the ,pleistocene1 mammoths were widespread over the ,united ,states1 and their remains are abundant in many stream deposits of this age4 ,proboscidean bones have been reported from ,pleistocene rocks in many parts of ,texas1 where they are commonly found in sand and gravel pits4 ,order ,perissodactyla4-- ,the perissodactyls1 or odd-toed animals1 are mammals in which the central toe on each limb is greatly enlarged4 ,modern representatives include the horses1 rhinoceroses1 and tapirs4 ,extinct members of the ,perissodactyla include the titanotheres1 chalicotheres1 and baluchitheres1 all of which grew to tremendous size and took on many unusual body forms4 ,,horses4-- ,one of the first perissodactyls was ,hyracotherium 7also called ,eohippus71 which is the earliest known horse 7,pl4 #dg74 ,this small animal1 whose remains have been found in ,big ,bend ,national ,park1 was about #a foot high and his teeth indicate a diet of soft food4 ,following the first horse1 there is a long series of fossil horses which provide much valuable information on the history of this important group of animals4 ,the record of the development of the horse is well represented in ,texas1 and the bones and teeth of fossil horses are common in certain parts of the ,state4 ,fossils of this type have been reported from the ,tertiary of the ,trans-,pecos1 ,gulf ,coastal ,plain1 and ,high ,plains regions of ,texas1 and the teeth of ,pleistocene horses have been found in sand and gravel pits in many parts of the ,state4 ,horse teeth 7fig4 #bf7 are particularly useful fossils as they may be accurately identified and used to determine the age of the rocks in which they are found4 ,illustration3 ,fig4 #bf4 ,typical ,pliocene horse tooth4 ,top view 7a7 and lateral view 7b7 of molar tooth 774 ,,titanotheres4-- ,this group of odd-toed mammals appeared first in the ,eocene1 at which time they were about the size of a sheep4 ,by ,middle ,oligocene time they had increased to gigantic proportions but still had a small and primitive brain4 ,brontotherium 7,pl4 #dh7 was slightly rhinoceros-like in appearance and is believed to be the largest land animal that ever inhabited the ,north ,american continent4 ,this animal was about #h feet tall at the shoulders2 a large bony growth protruded from the skull and this was extended into a flattened horn1 which was divided at the top4 ,illustration3 ,plate #dh ,,tertiary ,,mammals ,,uintatherium _/ ,,brontotherium _/ ,although the titanotheres underwent rapid development during the early ,tertiary1 these huge beasts became extinct during the middle of the ,oligocene epoch4 ,titanothere remains have been reported from the ,trans-,pecos region of ,texas4 ,,chalicotheres4-- ,the chalicotheres were in some ways like the titanotheres1 but they also exhibited many peculiarities of their own4 ,the head and neck of ,moropus1 a typical chalicothere1 were much like that of a horse1 but the front legs were longer than the hind legs1 and the feet resembled those of a rhinoceros except that they bore long claws instead of hoofs4 ,the chalicotheres lived in ,north ,america from ,miocene until ,pleistocene time but were probably never very numerous1 and their remains have not yet been discovered in ,texas4 ,,rhinoceroses4-- ,the rhinoceroses are also odd-toed animals1 and there are many interesting and well-known fossils in this group4 ,the woolly rhinoceros 7,pl4 #di7 was a ,pleistocene two-horned form that ranged from southern ,france to northeastern ,siberia4 ,the woolly rhinoceros is well known from complete carcasses recovered from the frozen tundra of ,siberia and from remains that were found preserved in an oil seep in ,poland4 ,these unusual specimens plus cave paintings made by early man have given a complete and accurate record of this creature4 ,although the woolly rhinoceros has not been reported from ,texas1 other fossil rhinoceroses have been found in the ,high ,plains and ,gulf ,coastal ,plain of ,texas4 ,these fossils have been found in rocks ranging from ,middle ,oligocene to late ,pliocene in age4 ,baluchitherium1 the largest land mammal known to science1 was a hornless rhinoceros that lived in late ,oligocene and early ,miocene time4 ,this immense creature measured approximately #be feet from head to tail1 stood almost #ah feet high at the shoulder1 and must have weighed many tons4 ,remains of these creatures have not been discovered in ,north ,america1 and they appear to have been restricted to ,central ,asia4 ,order ,artiodactyla4-- ,the artiodactyls are the even-toed hoofed mammals and include such familiar forms as pigs1 camels1 deer1 goats1 sheep1 and hippopotamuses4 ,this is a large and varied group of animals1 but the basic anatomical structure of the limbs and teeth show well the relationship between the different forms4 ,artiodactyls are abundant fossils in rocks ranging from ,eocene to ,pleistocene in age and are common in rocks of this age in ,texas4 ,,entelodonts4-- ,these giant pig-like artiodactyls lived during ,oligocene and early ,miocene time and were distinguished by a long heavy skull that held a relatively small brain4 ,the face was marked by large knobs which were located beneath the eyes and on the underside of the lower jaw1 and although these knob-like structures were blunt they had the appearance of short horns4 ,certain of these giant swine attained a height of #f feet at the shoulders and had skulls that measured #c feet in length 7,pl4 #df74 ,entelodont remains have been found in the ,miocene of the ,texas ,coastal ,plain4 ,,camels4-- ,the first known camels have been reported from rocks of upper ,eocene age1 and these small forms underwent considerable specialization of teeth and limbs as they developed in size4 ,many of the camels that lived during the middle ,cenozoic had long legs which were well adapted to running and long necks which would have allowed the animals to browse on the leaves of tall trees4 ,the earliest known ,texas camels were found in rocks of ,oligocene age1 and camels1 like horses1 must have been abundant in ,texas during the ,pleistocene for their fossilized remains are common in many parts of the ,state4 ,illustration3 ,plate #di ,,cenozoic ,,mammals ,,woolly ,,rhinoceros _/ ,,woolly ,,mammoth _/ ,,books ,,about ,,fossils ,the following books are recommended for the reader who wants to know more about fossils and fossil collecting4 ,the publications listed below cover various phases of historical geology and paleontology and range from children's books to the more technical publications of the professional paleontologist4 ,this list1 however1 is by no means all-inclusive and many other interesting and useful publications are available4 ,,general ,,works ,dunbar1 ,c4 ,o4 7#aiei7 ,historical geology1 ,john ,wiley and ,sons1 ,new ,york4 ,college-level text1 well written and well illustrated4 ,moore1 ,r4 ,c4 7#aieh7 ,introduction to historical geology1 ,mc,graw-,hill ,book ,co41 ,new ,york4 ,college-level presentation of earth history4 ,many illustrations of fossils4 ,moore1 ,ruth 7#aiec7 ,man1 time1 and fossils1 ,alfred ,knopf1 ,new ,york4 ,a readable account of fossils and their development throughout geologic time4 ,panghorn1 ,m4 ,w41 ,jr4 7#aieg7 ,earth for the layman1 ,american ,geological ,institute1 ,washington1 ,d4 ,c4 ,contains many valuable references4 ,raymond1 ,p4 ,e4 7#aiej7 ,prehistoric life1 ,harvard ,university ,press1 ,cambridge1 ,mass4 ,college-level text4 ,richards1 ,h4 ,g4 7#aiec7 ,record of the rocks1 ,ronald ,press1 ,new ,york4 ,college-level earth history text4 ,simpson1 ,g4 ,g4 7#aiec7 ,life of the past1 ,yale ,university ,press1 ,new ,haven1 ,conn4 ,thorough1 yet readable1 introduction to paleontology4 ,stirton1 ,r4 ,a4 7#aiei7 ,time1 life1 and man3 the fossil record1 ,john ,wiley and ,sons1 ,new ,york4 ,an introductory college text1 most of which is of interest to adult level general readers4 ,note3 ,see also sections on ,paleontology and ,fossils in ,encyclopedia ,americana1 ,encyclopaedia ,britannica1 and others4 ,,nontechnical ,,and ,,juvenile ,andrews1 ,r4 ,c4 7#aiec7 ,all about dinosaurs1 ,random ,house1 ,new ,york4 ,interesting and readable dinosaur book for junior high and high-school age4 ,andrews1 ,r4 ,c4 7#aief7 ,all about strange beasts of the past1 ,random ,house1 ,new ,york4 ,interesting and easy to read1 this book deals largely with extinct and unusual mammals 7junior high and high school74 ,colbert1 ,e4 ,h4 7#aide7 ,the dinosaur book1 ,american ,museum of ,natural ,history1 ,new ,york4 ,a classic among 8popular0 dinosaur books4 ,for all age levels4 ,colbert1 ,e4 ,h4 7#aieg7 ,dinosaurs1 ,american ,museum of ,natural ,history1 ,new ,york4 ,this little booklet provides a well-illustrated introduction to the dinosaurs4 ,for high school and adult-level readers4 ,dickinson1 ,alice 7#aied7 ,first book of prehistoric animals1 ,franklin ,watts1 ,inc41 ,new ,york4 ,easy to read1 well-illustrated book for grade-school age4 ,dunkle1 ,d4 ,h4 7#aieg7 ,the world of the dinosaurs1 ,smithsonian ,institution1 ,washington1 ,d4 ,c4 ,an easy to understand1 amply illustrated introduction to the dinosaurs 7high school-adult level74 ,fenton1 ,c4 ,l4 7#aicg7 ,life long ago1 ,the ,john ,day ,co41 ,new ,york4 ,very good for advanced grade and high-school age4 ,heal1 ,edith 7#aicj7 ,how the world began1 ,thomas ,s4 ,rockwell ,co41 ,chicago4 ,an account of the beginnings of life4 ,for upper grade through high-school age4 ,markman1 ,h4 ,c4 7#aied7 ,fossils1 ,denver ,museum of ,natural ,history1 ,denver1 ,colo4 ,a well-illustrated general survey of fossils4 ,for adult-level readers4 ,matthews ,,iii1 ,w4 ,h4 7#aifb7 ,fossils3 ,an introduction to prehistoric life1 ,barnes and ,noble1 ,inc41 ,new ,york1 8,in preparation0 at time of first printing of ,guidebook ,no4 #b4 ,this publication contains many collecting aids and much background material for amateur collectors4 ,contains also a brief review of earth history4 ,matthews ,,iii1 ,w4 ,h4 7#aifc7 ,wonders of the dinosaur world1 ,dodd1 ,mead ,co41 ,new ,york4 ,well illustrated1 non-technical presentation of dinosaurs4 ,for junior-high and high-school teachers4 ,parker1 ,b4 ,m4 7#aidb7 ,stories read from the rocks1 ,basic ,science ,education ,series1 ,row1 ,peterson and ,co41 ,evanston1 ,ill4 ,well written and colorfully illustrated4 ,for advanced grades and junior high4 ,parker1 ,b4 ,m4 7#aidh7 ,animals of yesterday1 ,basic ,science ,education ,series1 ,row1 ,peterson1 and ,co41 ,evanston1 ,ill4 ,well written and colorfully illustrated4 ,for advanced grades and junior high4 ,shaver1 ,r4 ,h4 7#aiei7 ,adventures with fossils1 ,geological ,survey1 ,indiana ,department of ,conservation1 ,bloomington1 ,ind4 ,collection hints and general information on fossils4 ,particularly for the lower grades4 ,shuttlesworth1 ,d4 ,e4 7#aieg7 ,real book of prehistoric life1 ,garden ,city ,books1 ,garden ,city1 ,n4 ,y4 ,survey of prehistoric life4 ,for grade and junior-high levels4 ,,collecting ,,helps ,brown1 ,vinson 7#aied7 ,how to make a home nature museum1 ,little1 ,brown and ,co41 ,boston4 ,contains suggestions for collecting1 mounting1 and displaying fossils and other objects of nature4 ,camp1 ,c4 ,l41 and ,hanna1 ,g4 ,d4 7#aicg7 ,methods in paleontology1 ,university of ,california ,press1 ,berkeley4 ,excellent discussion of collecting and preparation techniques4 ,casanova1 ,richard 7#aieg7 ,an illustrated guide to fossil collecting1 ,natureograph ,co41 ,san ,martin1 ,calif4 ,has collecting hints and fossil localities for most of the ,states4 ,collinson1 ,c4 ,c4 7#aiei7 ,guide for beginning fossil hunters1 ,educational ,series #d1 ,illinois ,state ,geological ,survey1 ,urbana4 ,clearly written1 well illustrated1 particularly for the lower grades4 ,goldring1 ,winifred 7#aiej7 ,handbook of paleontology for beginners and amateurs1 ,new ,york ,state ,museum1 ,albany1 ,n4 ,y4 ,a complete summary of paleontology4 ,for the advanced collector4 ,la ,rocque1 ,a41 and ,marple1 ,m4 ,f4 7#aiee7 ,ohio fossils1 ,ohio ,division of ,geological ,survey1 ,bulletin #ed1 ,columbus1 ,ohio4 ,rather comprehensive treatment of the invertebrates with several useful keys for fossil identification4 ,livingston1 ,v4 ,e41 ,jr4 7#aiei7 ,fossils in ,washington1 ,division of ,mines and ,geology1 ,department of ,conservation1 ,olympia1 ,wash4 ,an introduction to the geology and fossils of ,washington4 ,contains guide to collecting localities4 ,simpson1 ,b4 ,w4 7#aieh7 ,gem trails of ,texas1 ,bessie ,w4 ,simpson1 ,granbury1 ,texas4 ,field guide to ,texas mineral1 rock1 and fossil locations4 ,contains numerous maps and well-described collecting localities4 ,unklesbay1 ,a4 ,g4 7#aiee7 ,common fossils of ,missouri1 ,university of ,missouri ,bulletin1 ,handbook #d1 ,columbia1 ,mo4 ,written for the amateur2 contains much general information of interest to the beginning collector4 ,,reference ,,works ,arnold1 ,c4 ,a4 7#aidg7 ,an introduction to paleobotany1 ,mc,graw-,hill ,book ,co41 ,new ,york4 ,college-level textbook4 ,beerbower1 ,j4 ,r4 7#aifj7 ,search for the past1 ,prentice-,hall1 ,inc41 ,englewood ,cliffs1 ,n4 ,j4 ,good background text4 ,well illustrated4 ,has section on vertebrates4 ,colbert1 ,e4 ,h4 7#aiee7 ,evolution of the vertebrates1 ,john ,wiley and ,sons1 ,new ,york4 ,comprehensive and technical treatment of vertebrate fossils4 ,cushman1 ,j4 ,a4 7#aidh7 ,foraminifera1 their classification and economic use1 ,harvard ,university ,press1 ,cambridge1 ,mass4 ,college-level text containing large numbers of descriptions and illustrations of foraminifera4 ,easton1 ,w4 ,h4 7#aifj7 ,invertebrate paleontology1 ,harper ,bros41 ,inc41 ,new ,york4 ,college-level text4 ,good illustrations1 useful for identification4 ,fenton1 ,c4 ,l41 and ,fenton1 ,m4 ,a4 7#aieh7 ,the fossil book1 ,doubleday and ,co41 ,new ,york4 ,comprehensive1 easy-to-read1 beautifully illustrated treatment of all types of fossils4 ,jones1 ,d4 ,j4 7#aief7 ,introduction to microfossils1 ,harper and ,brothers1 ,new ,york4 ,college-level textbook with considerable information on collection1 preparation1 and the types of microfossils4 ,moore1 ,r4 ,c41 et al4 7#aiec-aiei7 ,treatise on invertebrate paleontology1 ,geological ,society of ,america and ,university of ,kansas1 ,lawrence1 ,kansas4 ,a technical reference for the more advanced collector4 ,it is issued in several parts and contains latest classification4 ,moore1 ,r4 ,c41 ,lalicker1 ,c4 ,g41 and ,fisher1 ,a4 ,g4 7#aiec7 ,invertebrate fossils1 ,mc,graw-,hill ,book ,co41 ,new ,york4 ,college-level reference with fine illustrations4 ,of value for purposes of identification4 ,romer1 ,a4 ,s4 7#aide7 ,vertebrate paleontology1 ,university of ,chicago ,press1 ,chicago4 ,a college-level textbook with numerous illustrations4 ,shimer1 ,h4 ,w4 7#aicc7 ,introduction to the study of fossils1 ,the ,macmillan ,company1 ,new ,york4 ,a relatively simple college-level presentation of plant and animal fossils4 ,shimer1 ,h4 ,w41 and ,shrock1 ,r4 ,r4 7#aidd7 ,index fossils of ,north ,america1 ,john ,wiley and ,sons1 ,new ,york4 ,comprehensive survey of the more common fossils of ,north ,america4 ,useful to the advanced collector and a most useful aid for fossil identification4 ,shrock1 ,r4 ,r41 and ,twenhofel1 ,w4 ,h4 7#aiec7 ,principles of invertebrate paleontology1 ,mc,graw-,hill ,book ,co41 ,new ,york4 ,useful college-level reference for advanced collectors4 ,,selected ,,references ,,on ,,texas ,,fossils#b 99,adkins1 ,w4 ,s4 7#aibj7 ,the ,weno and ,pawpaw formations of the ,texas ,comanchean3 ,univ4 ,texas ,bull4 #ahef4 ,descriptions and illustrations of many common ,cretaceous fossils4 99,adkins1 ,w4 ,s4 7#aibh7 ,handbook of ,texas ,cretaceous fossils3 ,univ4 ,texas ,bull4 #bhch4 ,lists all fossils described from the ,texas ,cretaceous prior to #aibh1 with many useful illustrations4 99,adkins1 ,w4 ,s41 and ,winton1 ,w4 ,m4 7#aiai7 ,paleontological correlation of the ,fredericksburg and ,washita formations of north-central ,texas3 ,univ4 ,texas ,bull4 #aide4 ,contains descriptions and illustrations of many common ,lower ,cretaceous fossils of north-central ,texas4 ,clarke1 ,w4 ,b41 and ,twitchell1 ,m4 ,w4 7#aiae7 ,the ,mesozoic and ,cenozoic ,echinodermata of the ,united ,states3 ,u4 ,s4 ,geological ,survey ,monograph #ed1 ,washington1 ,d4 ,c4 ,a valuable guide to the ,mesozoic and ,cenozoic echinoderms of ,texas4 99,frizzell1 ,d4 ,l4 7#aied7 ,handbook of ,cretaceous ,foraminifera of ,texas3 ,univ4 ,texas1 ,bureau ,econ4 ,geol4 ,rept4 ,inves4 ,no4 #bb4 ,a technical1 but invaluable aid in the study of ,texas ,cretaceous microfossils4 99,girard1 ,r4 ,m4 7#aiei7 ,bibliography and index of ,texas geology1 #aicc-aiej3 ,univ4 ,texas ,pub4 #eiaj4 ,this valuable reference guide contains many references to ,texas fossils4 ,note especially entries under ,paleontology in the index4 ,heuer1 ,edward 7#aieh7 ,comments on the nomenclature revision of the ,strawn and ,canyon megafossil plates1 in ,a guide to the ,strawn and ,canyon ,series of the ,pennsylvanian ,system in ,palo ,pinto ,county1 ,texas1 ,an ,occasional ,publication of the ,north ,texas ,geological ,society1 ,wichita ,falls1 ,texas4 ,contains illustrations and latest name changes of many of the more common ,pennsylvanian fossils of north ,texas4 99,king1 ,r4 ,e4 7#aicj7 ,geology of the ,glass ,mountains1 ,part ,,ii1 ,faunal summary and correlation of the ,permian formations with description of ,brachiopoda3 ,univ4 ,texas ,bull4 #cjdb4 ,contains descriptions and illustrations of numerous brachiopods from the ,glass ,mountains of ,trans-,pecos ,texas4 99,lee1 ,wallace1 et al4 7#aici7 ,stratigraphic and paleontologic studies of the ,pennsylvanian and ,permian rocks of north-central ,texas3 ,univ4 ,texas ,pub4 #chja4 ,contains an extensive faunal list and important collecting localities for ,pennsylvanian invertebrates4 99,moore1 ,r4 ,c41 and ,jeffords1 ,r4 ,m4 7#aidd7 ,description of lower ,pennsylvanian corals from ,texas and adjacent states3 ,univ4 ,texas ,pub4 #ddja1 pp4 #gg-bjh4 ,describes and illustrates many of the more common ,pennsylvanian corals4 99,plummer1 ,f4 ,b4 7#aidc7 ,the ,carboniferous rocks of the ,llano region of central ,texas3 ,univ4 ,texas ,pub4 #dcbi4 ,contains geologic map1 locality data1 and illustrations of many ,carboniferous fossils4 99,plummer1 ,f4 ,b41 and ,moore1 ,r4 ,c4 7#aiba7 ,stratigraphy of the ,pennsylvanian formations of north-central ,texas3 ,univ4 ,texas ,bull4 #bacb4 ,describes and illustrates many of the more common ,pennsylvanian fossils of north-central ,texas4 99,plummer1 ,f4 ,b41 and ,scott1 ,gayle 7#aicg7 ,upper ,paleozoic ammonites in ,texas3 ,univ4 ,texas ,bull4 #cgja1 pt4 #a4 99,renick1 ,b4 ,c41 and ,stenzel1 ,h4 ,b4 7#aica7 ,the lower ,claiborne of the ,brazos ,river1 ,texas3 ,univ4 ,texas ,bull4 #caja1 pp4 #gc-ajh4 ,contains discussion and illustrations of many common ,tertiary fossils4 ,sellards1 ,e4 ,h4 7#aiee7 ,texas through #bej million years3 ,museum ,notes ,no4 #d1 ,texas ,memorial ,museum1 ,austin4 ,this little booklet provides a short geologic history of ,texas along with a review of oil in ,texas4 99,sellards1 ,e4 ,h41 ,adkins1 ,w4 ,s41 and ,plummer1 ,f4 ,b4 7#aicc7 ,the geology of ,texas1 ,vol4 ,i1 ,stratigraphy3 ,univ4 ,texas ,bull4 #cbcb 7,august #bb1 #aicb74 ,this important publication will give the advanced collector much valuable information on the distribution of the rocks of ,texas4 ,complete with geologic map4 ,stanton1 ,t4 ,w4 7#aidg7 ,studies of some ,comanche pelecypods and gastropods3 ,u4 ,s4 ,geological ,survey ,prof4 ,paper #baa1 ,washington1 ,d4 ,c4 ,describes and illustrates most of the more common ,lower ,cretaceous pelecypods and gastropods of the ,state4 99,stenzel1 ,h4 ,b41 ,krause1 ,e4 ,k41 and ,twining1 ,j4 ,t4 7#aieg7 ,pelecypoda from the type locality of the ,stone ,city beds 7,eocene7 of ,texas3 ,univ4 ,texas ,pub4 #egjd4 ,descriptions and illustrations of many of the more common ,tertiary clams and oysters4 99,stephenson1 ,l4 ,w4 7#aida7 ,the larger invertebrate fossils of the ,navarro group of ,texas3 ,univ4 ,texas ,pub4 #daja4 ,contains descriptions of many common ,upper ,cretaceous invertebrates 7exclusive of corals and crustaceans74 ,stephenson1 ,l4 ,w4 7#aieb7 ,larger invertebrate fossils of the ,woodbine formation 7,cenomanian7 of ,texas3 ,u4 ,s4 ,geological ,survey ,prof4 ,paper #bdb1 ,washington1 ,d4 ,c4 99,winton1 ,w4 ,m4 7#aibe7 ,the geology of ,denton ,county3 ,univ4 ,texas ,bull4 #bedd4 ,illustrates and discusses the occurrence of many ,cretaceous fossils4 99,winton1 ,w4 ,m41 and ,adkins1 ,w4 ,s4 7#aibj7 ,the geology of ,tarrant ,county3 ,univ4 ,texas ,bull4 #aica4 ,contains many illustrations of common north ,texas ,cretaceous fossils4 ,,glossary ,amber--a hard1 yellowish1 translucent1 fossilized plant resin4 ,ammonite--ammonoid cephalopod with complexly wrinkled suture pattern2 member of subclass ,ammonoidea4 ,anterior--front or fore4 ,anus--the terminal opening of the alimentary canal1 through which waste matter is discarded from the body4 ,aperture--the opening of shells1 cells1 etc4 ,aragonite--calcium carbonate 7,ca,c,o7 crystallizing in a different form than calcite4 ,in shells it is chalky and opaque2 is less stable than calcite4 ,archeozoic--the oldest known geological era2 early ,precambrian time4 ,articulated--joined by interlocking processes or by teeth and sockets4 ,asymmetrical--without or lacking symmetry4 ,bilateral--pertaining to the two halves of a body as symmetrical and mirror images of each other4 ,binomial nomenclature--system of scientific nomenclature requiring two names3 generic and trivial4 ,blastoid--stalked echinoderm with bud-like calyx usually consisting of #ac plates2 member of class ,blastoidea4 ,brachiopod--bivalved marine invertebrate2 member of phylum ,brachiopoda4 ,brackish--a mixture of salt and fresh waters4 ,burrow--a hole in the ground1 rock1 wood1 etc41 made by certain animals for shelter or while gathering food4 ,calcareous--composed of1 or containing1 calcium carbonate2 limy4 ,calcite--calcium carbonate 7,ca,c,o7 crystallizing in a different form than aragonite4 ,in shells it is translucent and more stable than aragonite4 ,cambrian--the first 7oldest7 period of the ,paleozoic era4 ,calyx--in corals the bowl-shaped depression in the upper part of the skeleton2 in stalked echinoderms that part of the body which contains most of the soft parts4 ,caprinid--a ,cretaceous pelecypod that is typically coiled in the form of a ram's horn4 ,carapace--the hard protective covering that forms the exoskeleton of many invertebrates2 in arthropods it is usually chitinous or calcaro-chitinous4 ,carbonization--the process of fossilization whereby organic remains are reduced to carbon or coal4 ,cast--the impression taken from a mold4 ,cenozoic--the latest era of geologic time1 following the ,mesozoic era and extending to the present4 ,cephalon--the head2 in trilobites the anterior body segment forming the head4 ,cephalopod--marine invertebrate with well-defined head and eyes and with tentacles around the mouth2 member of class ,cephalopoda1 phylum ,mollusca2 includes squids1 octopuses1 pearly nautilus4 ,ceratite--an ammonoid cephalopod with suture composed of rounded saddles and jagged lobes2 member of subclass ,ammonoidea4 ,chert--a cryptocrystalline variety of silica2 flint is a variety of chert4 ,chitin--a horn-like substance1 found in the hard parts of many animals1 such as beetles1 crabs1 etc4 ,chitinous--composed of chitin4 ,cirri--in crinoids1 the jointed appendages which branch off the side of the stem or from the base of some crinoid stems4 ,coelenterate--invertebrates characterized by a hollow body cavity1 radial symmetry1 and stinging cells2 a member of phylum ,coelenterata2 includes jellyfishes1 corals1 sea anemones4 ,colonial--in biology refers to the way in which some invertebrates live in close association with1 and are more or less interdependent upon1 each other2 colonial corals1 hydroids1 etc4 ,columella--a small column or central axis2 in corals the small rod or axial pillar in the center of the corallite2 in gastropods the solid or perforate pillar formed by the union of the successive coils of a conispiral shell4 ,columnal--one of the disk-shaped segments of a crinoid stalk4 ,concentric--having a common center1 as circles2 refers to shell markings that are parallel to shell margin4 ,concretion--nodular or irregular masses in sedimentary rocks and usually formed around a central core1 which is often a fossil4 ,conical--cone-shaped4 ,conodont--minute tooth-like fossils found in certain ,paleozoic rocks2 their origin is not definitely known1 but they may have been part of some type of extinct fish4 ,coral--bottom-dwelling marine invertebrate that secretes calcareous hard parts2 member of class ,anthozoa1 phylum ,coelenterata4 ,corallite--the skeleton formed by an individual coral animal2 may be solitary or form part of a colony4 ,corallum--the skeleton of a coral colony4 ,corona--crown2 in echinoids the main part of the skeleton consisting of symmetrically arranged calcareous plates4 ,coprolite--the fossil excrement of animals4 ,correlation--the process of demonstrating that certain strata are closely related to each other or that they are stratigraphic equivalents4 ,cretaceous--the third and last period of the ,mesozoic era4 ,cystoid--an extinct stemmed echinoderm with calyx composed of numerous irregularly arranged plates2 member of class ,cystoidea4 ,dendritic--resembling a tree1 branching4 ,dentition--the system or arrangement of teeth peculiar to any given animal4 ,devonian--the fourth oldest period of the ,paleozoic era1 follows the ,silurian1 precedes the ,mississippian4 ,dip--the angle of inclination which the bedding plane of rocks makes with a real or imaginary horizontal line4 ,distillation--in fossils that process by which volatile organic matter is removed1 leaving a carbon residue4 ,dolomite--a mineral composed of calcium magnesium carbonate 7,ca,mg7,,co774 ,dorsal--pertaining to the back4 ,echinoderm--a marine invertebrate with calcareous exoskeleton and usually exhibiting a five-fold radial symmetry2 member of phylum ,echinodermata2 includes cystoids1 blastoids1 crinoids1 starfishes1 and sea urchins4 ,echinoid--bottom-dwelling1 unattached marine invertebrate with exoskeleton of calcareous plates covered by movable spines2 member of class ,echinoidea2 sea urchins1 heart urchins1 biscuit urchins4 ,endoskeleton--the internal supporting structure of an animal4 ,eocene--the next to earliest of the ,tertiary epochs1 follows the ,paleocene and precedes the ,oligocene4 ,equivalved--right and left valves subequal and 7except for hinge structures7 comprising mirror images of each other4 ,evolution--a term applied to those methods or processes and to the sum of those processes whereby organisms change through successive generations4 ,exoskeleton--an external skeleton1 or hard covering for the protection of soft parts1 particularly among invertebrates4 ,fault--the displacement of rocks along a zone of fracture4 ,fauna--an assemblage of animals 7living or fossil7 living in a given place at a given time4 ,flank--the side or lateral portion of anything4 ,flora--an assemblage of plants 7living or fossil7 living in a given place at a given time4 ,fold--in brachiopods1 a major rounded elevation of shell which affects both inner and outer shell surfaces4 ,foramen--in brachiopods1 the opening in the pedicle valve near the beak where the pedicle extends through the shell4 ,foraminifer--a protozoan usually possessing a calcareous1 perforated1 chambered shell1 but shell may be chitinous or agglutinated2 a member of the order ,foraminifera1 phylum ,protozoa4 ,formation--a rock unit useful for mapping and distinguished primarily on the basis of lithologic characters4 ,fossil--the remains or traces of organisms buried by natural causes and preserved in the earth's crust4 ,guide fossil--a fossil which1 because of its limited vertical but wide horizontal distribution1 is of value as a guide or index to the age of the rocks in which it is found4 ,fossiliferous--containing fossilized organic remains4 ,fusulinid--a spindle-shaped foraminifer3 test shaped like a grain of wheat4 ,gastrolith--highly polished well-rounded pebbles found associated with certain reptilian fossils2 8stomach stones40 ,gastropod--a terrestrial or aquatic invertebrate1 typically possessing a single-valved1 calcareous1 coiled shell2 member of class ,gastropoda1 phylum ,mollusca3 snails and slugs4 ,geologic age--the age of an object as stated in terms of geologic time 7e4g41 a ,pennsylvanian fern1 ,cretaceous dinosaur74 ,geologic map--map showing distribution of rock outcrops1 structural features1 mineral deposits1 etc4 ,geologic range--the known duration of an organism's existence throughout geologic time 7e4g41 ,cambrian to ,recent for brachiopods74 ,glauconite--a greenish mineral commonly formed in marine environments and essentially a hydrous silicate of iron and potassium4 ,goniatite--an ammonoid cephalopod with suture composed of smooth saddles and simple angular lobes2 member of subclass ,ammonoidea4 ,graptolite--an extinct1 marine1 colonial organism with chitinous hard parts2 believed to belong to subphylum ,hemichordata of phylum ,chordata4 ,guide fossil--see ,fossil4 ,habitat--the physical environment in which an organism lives4 ,hinge-line--in brachiopods1 the edge of the shell where the two valves articulate2 in pelecypods1 the dorsal margin of the valve which is in continual contact with the opposite valve4 ,igneous rock--rocks which have solidified from lava or molten rock called magma4 ,index fossil--see ,fossil4 ,inequivalved--opposite valves unlike in shape or size1 or both4 ,jurassic--second oldest period of the ,mesozoic2 follows the ,triassic1 precedes the ,cretaceous4 ,keel--a strong continuous ridge along the ventral side of ammonites4 ,larva--the young form of some animals before they assume the mature shape4 ,lateral--side or to the side4 ,lithology--the study and description of rocks based on the megascopic 7with the naked eye7 examination of samples4 ,used also to refer to the texture and composition of any given rock sample4 ,living chamber--in mollusks1 that part of the shell which is occupied by the living animal4 ,lobe--in cephalopods1 the backward flexure of the suture or septum4 ,longitudinal--in a direction parallel with the length4 ,lophophore--in brachiopods1 a tentacle-bearing appendage attached to the anterior surface of the mantle cavity4 ,mantle--in mollusks and brachiopods1 a layer of tissue containing cells that secrete the shell4 ,meso---a prefix signifying middle4 ,mesozoic--that era of geologic time that precedes the ,cenozoic and follows the ,paleozoic4 ,miocene--fourth oldest epoch of the ,tertiary period2 follows the ,oligocene1 precedes the ,pliocene4 ,mississippian--fifth oldest period of the ,paleozoic3 follows the ,devonian1 precedes the ,pennsylvanian4 ,multicellular--composed of more than one cell4 ,nacreous--pearly4 ,node--a knob4 -oid--a suffix meaning 8in the form of40 ,oligocene--the third oldest epoch of the ,tertiary period3 precedes the ,miocene1 follows the ,eocene4 ,operculum--the lid or covering of the aperture of certain shells4 ,oral--referring to the mouth or aperture4 ,orbitoidids--foraminifers with large typically disk-shaped tests4 ,ordovician--second oldest period of the ,paleozoic era2 follows the ,cambrian1 precedes the ,silurian4 ,ossicle--loosely used as a small plate4 ,paleocene--oldest epoch of the ,tertiary period2 precedes the ,eocene4 ,paleozoic--that era of geologic time that follows ,precambrian time and precedes the ,mesozoic era4 ,pedicle opening 7pedicle foramen7--see ,foramen4 ,pelecypod--a bivalved aquatic invertebrate2 member of class ,pelecypoda1 phylum ,mollusca4 ,pennsylvanian--the sixth oldest period of the ,paleozoic era2 follows the ,mississippian1 precedes the ,permian4 ,period--a division of geologic time 7,pl4 #a74 ,periostracum--the horny outer covering or epidermis on shells4 ,permian--seventh and last period of the ,paleozoic4 ,permineralization--that process by which mineral matter has been added to the original shell material by precipitation in the interstices rather than replacing the original shell material4 ,phosphatic--containing or pertaining to phosphate minerals4 ,phylum--one of the primary divisions of the animal or vegetable kingdoms4 ,planispiral--shell coiled in one plane4 ,pleistocene--earliest epoch of ,quaternary period1 ,cenozoic era2 follows ,pliocene epoch of ,tertiary period1 precedes ,recent epoch of ,quaternary4 ,pleural--referring to the side or ribs2 in trilobites1 refers to lateral portions of thorax and pygidium4 ,pliocene--latest epoch of ,tertiary period of ,cenozoic era2 follows ,miocene epoch and precedes ,pleistocene epoch of ,quaternary period4 ,polygonal--many sided or having many-sided plates4 ,polyp--a many-tentacled aquatic coelenterate animal1 typically cylindrical or cup-shaped1 as in corals4 ,porcelaneous--like porcelain4 ,pore--a very small opening4 ,posterior--situated behind2 to the rear4 ,precambrian--that portion of geologic time before the ,cambrian2 divided into ,archeozoic era 7,early ,precambrian7 and ,proterozoic era 7,late ,precambrian74 ,protero--combining form meaning fore1 former1 or anterior in time 7,greek proteros1 fore74 ,proterozoic--youngest era of the ,precambrian2 follows the ,archeozoic era and precedes the ,cambrian period of the ,paleozoic era4 ,protista--the organic kingdom including the simplest of all one-celled organisms which possess various characters of both plants and animals2 bacteria1 algae1 foraminifers1 radiolarians4 ,protoconch--in mollusks1 the initial chamber of shell4 ,pyrite--a hard1 brass-yellow mineral composed of iron sulfide2 8fool's gold40 ,quaternary--the youngest period of the ,cenozoic era1 follows the ,tertiary period4 ,radial symmetry--see ,symmetry4 ,reef--a mound-like or ridge-like elevation of the sea bottom which almost reaches the surface of the water1 composed primarily of organic material and commonly formed by reef-building animals1 such as corals and oysters4 ,replacement--type of fossilization whereby hard parts of organisms are removed by solution accompanied by almost simultaneous deposition of other substances in the resulting voids2 mineralization4 ,respiration--the process of oxygenation4 ,rock--an aggregation of one or more minerals4 ,rock-unit--divisions of rocks based on definite physical and lithologic characteristics and not defined on the basis of geologic time alone2 groups1 formations1 members4 ,rudistid--a ,cretaceous pelecypod that does not exhibit the typical clam or oyster shape2 many are cone-shaped1 resembling corals4 ,saddle--in cephalopods1 the forward flexure 7curved toward the aperture7 of the suture or septum4 ,scaphopod--an exclusively marine mollusk with a single-valved tusk-shaped shell2 member of class ,scaphopoda1 phylum ,mollusca4 ,scavenger--an animal that feeds on organic refuse4 ,sedentary--stationary in life1 not moving from place to place4 ,sediment--material that has been deposited by settling from a transportation agent such as water or air2 typically composed of weathered rock fragments4 ,sedimentary rock--rocks formed from the accumulation and lithification of sediments4 ,segment--one of the parts into which a body naturally separates or is divided2 for example1 segments of arthropods or annelid worms4 ,septal--pertaining to the septum4 ,septum 7plural1 septa7--a dividing wall or partition2 in fusulinids1 a partition between chambers in the fusulinid shell2 in corals1 one of the radiating1 longitudinal1 calcareous plates located within the corallite2 in cephalopods1 the transverse partitions between the chambers4 ,series--the rocks formed during an epoch2 the time-stratigraphic term next in rank below a system4 ,serrate--notched like a saw4 ,sessile--animal attached to the sea floor more or less permanently4 ,silica--an oxide of silicon 7,si,o74 ,siliceous--containing or pertaining to silica4 ,silicification--the process of combining or impregnating with silica4 ,silurian--the third oldest period of the ,paleozoic era2 follows the ,ordovician1 precedes the ,devonian4 ,sinus--an elongate depression on brachiopod shells4 ,siphuncle--in cephalopods1 the segmented horny or calcareous tube which extends from the protoconch to the living chamber4 ,slickensides--polished and grooved surfaces that are the result of two rock masses sliding past each other as in faulting4 ,solitary--living alone2 not part of a colony4 ,species--one of the smaller natural divisions in classification4 ,specific name--see ,trivial name4 ,spicule--a minute spike or dart1 skeletal element in sponges and holothurians4 ,stratum 7plural1 strata7--a single bed or layer of rock4 ,strike--the direction of a real or imaginary line that is formed by the intersection of a bed or stratum with a horizontal plane2 strike is perpendicular to the dip4 ,subconical--less than conical in shape2 almost a cone4 ,suture--the line of junction between two parts2 in crinoids1 the line of junction between two plates2 in gastropods1 the line of junction of the whorls as seen on the exterior of the shell2 in cephalopods1 the line of junction between a septum and the shell wall4 ,symmetry--orderly arrangement of parts of an object with reference to lines1 planes1 or points4 ,bilateral symmetry--the symmetrical duplication of parts on each side of a vertical anterior-posterior plane4 ,radial symmetry--the symmetrical repetition of parts around a common vertical dorso-ventrally disposed axis4 ,pentamerous symmetry--symmetry arranged in a pattern of fives4 ,system--the rocks formed during a period2 the time-stratigraphic term next in rank above a series4 ,taxonomy--that branch of science that deals with classification1 especially in relation to plants1 animals1 or fossils4 ,tertiary--the oldest period of the ,cenozoic era2 follows the ,cretaceous period of the ,mesozoic and precedes the ,quaternary period of the ,cenozoic4 ,test--the protective covering of some invertebrate animals4 ,theca--a sheath or case2 in coelenterates1 the bounding wall at or near the margin of the exoskeleton2 in echinoderms1 the main body skeleton 7or calyx7 which houses the animal's soft parts2 in graptolites1 any cup or tube of the colony4 ,thorax--in trilobites1 that part of the body between the cephalon and pygidium4 ,time-unit--a portion of continuous geologic time 7e4g41 eras1 periods1 epochs1 and ages74 ,time-rock unit--same as time-stratigraphic unit4 ,time-stratigraphic unit--term given to rock units with boundaries established by geologic time2 strata deposited during definite portions of geologic time 7e4g41 systems1 series1 stages1 etc474 ,topography--the physical features or configuration of a land surface4 ,topographic map--a map showing the physical features of an area1 especially the relief and contour of the land4 ,transverse--at right angles to length4 ,triassic--the youngest period of the ,mesozoic era2 follows the ,permian period of the ,paleozoic and precedes the ,jurassic period of the ,mesozoic4 ,trilobite--an extinct marine arthropod having a flattened segmented body covered by a hardened dorsal exoskeleton divided into three lobes4 ,trivial name--the ,latinized name added to a generic name to distinguish the species2 same as specific name4 ,type locality--the geographic location at which a formation was first described and from which it was named2 or from which the type specimen of a fossil species comes4 ,type specimen--the individual or specimen on which the original designation of a species was established4 ,umbilicus--an external depression or opening at the center of many loosely coiled shells2 in gastropods it is usually located at the base of the shell2 in cephalopods it is usually located laterally4 ,umbo--the arched part of the valve near the beak in bivalve shells4 ,unicellular--composed of one cell4 ,valve--the one or more pieces comprising the shell of animals4 ,variety--a subdivision of a species1 designated by a third name when a variety is designated4 ,ventral--pertaining to the abdomen2 as opposed to dorsal1 pertaining to the back4 ,vertebrate--an animal having a backbone or spinal column4 ,whorl--a single turn or volution of a coiled shell4 -zoic--combining form meaning 8life0 7,greek zoikos1 life74 ,zooecium 7plural1 zooecia7--tube or chamber occupied by an individual of the bryozoan colony2 also called an autopore4 ,footnotes #a;,associate ,professor of ,geology1 ,lamar ,state ,college of ,technology1 ,beaumont1 ,texas4 #b;,entries marked with asterisk are published by the ,bureau of ,economic ,geology1 ,the ,university of ,texas1 ,austin4 ,those not out of print are distributed at nominal sale price2 list sent on request4 ,these publications may be consulted at many public libraries and_/or ,chamber of ,commerce offices4 ,index ,page numbers in italics indicate illustrations4 ,a ,acanthoceras3 #gg ,actinomma3 #di ,africa3 #hg ,agnatha3 #hg ,alaska3 #g ,alectryonia lugubris3 #fh algae3 #dd1 #df1 #dg 8algal biscuits03 #dd alligators3 #ie ,allorisma3 #fg ,allosaurus3 #ij1 #ig1 #ih ,allotheria3 #ajj allotherians3 #ajj ,amarillo ,college3 #bg amber3 #g amblypods3 #ajb ,ambocoelia3 #eg ,amelanchier3 #dh ,american ,museum of ,natural ,history3 #b1 #ae1 #if ammonites3 #aa1 #ge1 #gf1 #gg1 #gh ,ammonoidea3 #ff ammonoids3 #ge1 #gf1 #gg1 #gh ,amphibia3 #hi amphibians3 #hg1 #ib ,amphineura3 #ef ,amphiscapha3 #fa ,ancilla3 #fd ,angulotreta3 #ee1 #ef ankylosaurs3 #ij1 #ig1 #ii ,annelida3 #gh annelids3 #gh ,anomia3 #gd anteaters3 #ajj ,anthozoa3 #di1 #ea ,apsotreta3 #ee1 #ef aragonite3 #aa ,archelon3 #ia ,archetectonica3 #fd ,archaeopteryx3 #ajj ,archeozoic1 derivation and pronunciation3 #cc ,archer ,county3 #hi ,archimedes3 #ed arietina1 ,exogyra3 #gj ,aristotle3 #c ,arizona3 #g ,arkansas3 #cg ,arlington ,state ,college3 #a1 #bg armadillos3 #ajj1 #ajb ,aronow1 ,saul3 #a ,arthropoda3 #gh1 #gi1 #hj arthropods3 #aj1 #gh1 #gi1 #hj crustaceans3 #gi1 #hj insects3 #g1 #gi ostracodes3 #gi1 #hj trilobites3 #gh1 #hj ,articulata3 #ef ,artiodactyla3 #ajf artiodactyls3 #ajf camels3 #ajf entelodonts3 #aja1 #ajf ash1 volcanic3 #e ,astacodes3 #gi ,astartella3 #fg ,asteroidea3 #hb asteroids3 #hb1 #hc ,asterozoa3 #hb ,astraeospongium3 #ej ,astrhelia3 #ec ,astylospongia3 #ej ,aulosteges tuberculatus3 #ab1 #ac ,austin3 #ad1 #ag1 #ai1 #hg ,austin ,college3 #bg ,australia3 #hg author1 of a fossil3 #bb autopores3 #ea ,aves3 #hi1 #ajj ,avonia3 #ab1 #ac signata3 #ab1 #ac subhorrida3 #ab1 #ac ,b bacteria3 #dg ,baculites3 #gg bags1 collecting3 #ag1 #ah ,balcones fault zone3 #cf1 #cg baluchitheres3 #ajd1 #ajf ,baluchitherium3 #ajf ,barbatia3 #gd ,baylor ,county3 #hi ,baylor ,university3 #a1 #b1 #bg1 #ij1 #ia1 #ie ,beaumont3 #a1 #cd clay3 #cd ,beaver1 ,harold3 #a ,belemnites3 #gg1 #gh ,belemnoidea3 #gh belemnoids3 #gg1 #gh ,bellerophon3 #fa ,big ,bend area3 #ce1 #cf ,national ,park3 #ce1 #ig1 #ajb ,big ,spring3 #hi binomial nomenclature3 #ba-bb ,bird1 ,r4 ,t43 #b1 #ae1 #if birds1 fossil3 #e1 #ajj ,blastoidea3 #ha blastoids3 #bf1 #bh1 #ha ,blinn ,college3 #bg bone1 permineralized3 #i ,books ,about ,fossils3 #ajh-aaj ,boon1 ,jack3 #a ,brachiopoda3 #ed1 #ee1 #ef brachiopods3 #bf1 #bi1 #ed1 #ee1 #ef articulate3 #ed1 #ee1 #ef1 #eg1 #eh ,cambrian3 #ee ,cretaceous3 #ef inarticulate3 #ee1 #ef ,mississippian3 #ee ,pennsylvanian3 #eg1 #eh ,permian3 #ab1 #ac ,recent3 #ef silicified3 #ab1 #ac symmetry3 #bd1 #bf1 #bi ,brachiosaurus3 #ij ,brewster ,county3 #aa1 #ab1 #ce1 #da brittle stars3 #hb ,bronaugh1 ,richmond ,l43 #a ,brontosaurus3 #ij1 #ig1 #ih ,brontotherium3 #ajd1 #aje1 #ajf ,brown1 ,l4 ,f41 ,jr43 #a ,bryophyta3 #dd ,bryozoa3 #ea1 #ed1 #ee bryozoans3 #bf1 #bg1 #bh1 #cj1 #ea1 #ed1 #ee1 #hd ,mississippian3 #ed ,pennsylvanian3 #ee bulla1 ,venericardia3 #gb ,bureau of ,economic ,geology3 #b1 #ai burrows3 #ad 8button corals03 #di1 #ec ,c ,calamites3 #dh calcite3 #aj1 #aa callus3 #ei ,calyptraphorus3 #fd ,camarotoechia3 #ee ,cambrian-- derivation and pronunciation3 #cd fossils3 #dj brachiopods3 #ee graptolites3 #hf of ,franklin ,mountains1 ,llano1 ,marathon1 and ,solitario uplifts3 #dj camels3 #ajf cameratus1 ,neospirifer3 #eh ,caninia3 #ea1 #eb ,canis diris3 #ajb1 #ajc domestica3 #bb caprinid3 #bg1 #cj caprock1 of ,high ,plains3 #ce carbon residues3 #aj1 #hf ,carboniferous3 #cd carinata1 ,ostrea3 #ga ,carnivora3 #ajb carnivores3 #ajb1 #ajc ,caryocorbula3 #gd ,caryocrinites3 #ha ,casey1 ,josephine3 #b casts3 #aa catalog1 fossil2 number3 #ca cement1 portland3 #ai ,cenozoic-- derivation and pronunciation3 #cc periods of3 #cd rocks in ,texas3 #dc central ,asia3 #ajf central ,texas3 #aa1 #db ,cephalopoda3 #ef1 #ff1 #ge1 #gh cephalopods3 #bd1 #bf1 #bg1 #bh1 #bi1 #cj1 #ff1 #ge1 #gf1 #gg1 #gh ammonites3 #ge1 #gf1 #gg1 #gh ammonoids3 #ge1 #gf1 #gg1 #gh belemnoids3 #gg1 #gh ceratites3 #ge1 #gh coleoids3 #gg1 #gh cuttlefish3 #gh goniatites3 #ge1 #gf nautiloids3 #ff1 #ge1 #gf octopus3 #ff1 #gh squid3 #ff1 #gh sutures3 #ff1 #ge1 #gh ceratites3 #ge1 #gh ceratopsians3 #ij1 #ii1 #ajj ,ceratosaurus3 #ij ,cerithium3 #fb chalicotheres3 #ajd1 #ajf ,chelonia4 ,see turtles4 chisels3 #ag chitin3 #aj chitons3 #ef ,chondrichthyes3 #hg ,chonetes3 #eg ,chordata3 #hd-ajb chordates3 #hd amphibians3 #hi1 #ib birds3 #ajj fishes3 #hg1 #hh1 #hi graptolites3 #dj1 #hd1 #hf mammals3 #ajj-ajg reptiles3 #hi-ajj ,cladochonus3 #ea1 #eb ,cladophyllia3 #ec clams3 #aa1 #ef1 #ei4 ,see also pelecypods4 class1 taxonomic3 #bb classification1 binomial nomenclature3 #ba-bb units of3 #bb club mosses3 #dg coal3 #bj1 #dg mines3 #bj1 #dg plants3 #af1 #df1 #dg1 #dh ,cochlespiropsis3 #fc ,coelenterata3 #di1 #ea1 #hd coelenterates3 #di1 #ea-ec ,coleoidea3 #ff coleoids3 #gg1 #gh collecting bags3 #ag1 #ah columella1 corals3 #ea gastropods3 #ei1 #fj columnal1 crinoid3 #ha1 #hb1 #hc ,comanchean series of ,cretaceous3 #cd4 ,see also ,lower ,cretaceous4 compass3 #ai ,composita subtilita3 #eg compound corals4 ,see corals1 colonial4 concretions3 #af coniferous trees3 #g conodonts3 #da1 #hh1 #hi ,conus3 #fc ,cooper1 ,g4 ,a43 #b1 #ab coprolites3 #ad corallite3 #di1 #ea corallum3 #ea corals3 #aa1 #bd1 #bf1 #bg1 #di1 #ea1 #eb1 #ec 8button03 #di1 #ec colonial3 #bd1 #bg1 #cj1 #ea1 #eb1 #ec ,cretaceous3 #ec 8horn03 #di1 #ea1 #eb morphology3 #ea ,pennsylvanian3 #eb polyp3 #di solitary3 #bd1 #bh1 #bi1 #cj1 #di1 #ea1 #eb1 #ec symmetry3 #bd1 #bf1 #bg1 #bh1 #bi1 #cj ,tertiary3 #ec ,cordaites3 #dh correlation3 #cb ,corythosaurus3 #ij cotylosaurs3 #hi1 #ib crabs3 #gh1 #gi ,crassatella3 #gb crayfish3 #gh creodonts3 #ajb ,cretaceous-- ,see also ,comanchean and ,gulf series4 derivation and pronunciation3 #cd fossils3 #db-dc arthropods3 #gi brachiopods3 #ef cephalopods3 #ff1 #fg1 #gf1 #gg corals3 #ec crocodiles3 #ie1 #if dinosaurs3 #ij1 #ia1 #ic1 #id1 #ie1 #ig1 #ii echinoderms3 #hc1 #hd1 #he foraminifers3 #di gastropods3 #ei1 #fb nautiloids3 #gf pelecypods3 #ei1 #ff1 #fh-ga shark teeth3 #hh worms3 #gh tubes3 #i of central ,texas1 ,edwards ,plateau1 ,gulf ,coastal ,plain1 ,high ,plains1 north ,texas1 and ,trans-,pecos ,texas3 #db 8,pyrite ,fossil ,zone0 of3 #aa crinoidal limestone3 #da1 #hb1 #hc ,crinoidea3 #ha crinoids3 #bf1 #bh1 #da1 #ha1 #hb1 #hc calyx3 #ha1 #hb1 #hc morphology3 #ha stems3 #bf1 #bh1 #ha1 #hb1 #hc ,crockett ,county3 #db ,crockett formation3 #dc crocodiles3 #ie1 #if crossopterygians3 #hg crustaceans3 #gi1 #hj ,culberson ,county3 #ce cuttlefish3 #gh cycads3 #dg1 #dh ,cymatoceras3 #ge1 #gf ,cystoidea3 #ha cystoids3 #ha1 #hb1 #hc ,d 8,dark ,ages03 #c da ,vinci1 ,leonardo3 #c ,davis1 ,darrell3 #a ,decapoda4 ,see ,coleoidea4 deer3 #ajf ,del ,mar ,college3 #bg dendrites3 #ad ,dendrograptus3 #hf ,denver1 ,colorado3 #ai ,derbya3 #eg ,devonian-- derivation and pronunciation3 #cd fossils3 #da placoderms3 #hg1 #hh ,psilophyton3 #dh of ,el ,paso and ,van ,horn regions1 ,llano and ,marathon uplifts3 #da ,diablo ,mountains3 #da diatoms3 #dd1 #df1 #dg ,dibranchiata4 ,see ,coleoidea4 ,dictyoclostus3 #ee ,dimetrodon3 #ib ,dinobastis3 #ajb1 #ajc ,dinocerata3 #ajb dinocerates3 #ajb1 #aje dinosaurs3 #hi1 #ij-id1 #ie1 #if1 #ig1 #ih1 #ii1 #ajj armored3 #ij1 #ig1 #ii1 #ajj duck-billed3 #ij1 #ig1 #ii flying3 #ia1 #id1 #ie horned3 #ij1 #ii1 #ajj plate-bearing3 #ij1 #ig1 #ii swimming3 #ia1 #ic1 #ie ,diplodocus3 #ij ,diplograptus3 #hf dire wolf3 #ajb1 #ajc diris1 ,canis3 #ajb1 #ajc distillation3 #aj ,distorsio3 #fc division1 plant3 #dd ,dixon1 ,j4 ,w41 ,jr43 #b1 #ij1 #ia dolomite3 #aa dolphins3 #ie domestica1 ,canis3 #bb ,du,bar1 ,jules3 #a ,dufrenoyia3 #gg ,e ,eastland ,county3 #bj ,east ,texas ,state ,college3 #bg ,echinodermata3 #hj-hd echinoderms3 #hj-hd asteroids3 #hb1 #hc blastoids3 #ha crinoids3 #ha1 #hb1 #hc cystoids3 #ha1 #hb1 #hc echinoids3 #hb1 #hd1 #he holothuroids3 #hd sclerites3 #hc ,echinoidea3 #hb echinoids3 #bf1 #bh1 #bi1 #hb1 #hd1 #he ,cretaceous3 #hd1 #he plates3 #hd1 #he spines3 #hd1 #he ,echinozoa3 #hb ,edentata3 #ajj edentates3 #ajj1 #aja1 #ajb ,edwards ,plateau3 #ai1 #cf1 #cg1 #db1 #dc ,egyptian desert3 #c ,elasmosaurus3 #ia elephants3 #ajb ,eleutherozoa3 #hb ,ellison1 ,samuel ,p43 #a ,el ,paso region-- ,devonian of3 #da ,ordovician of3 #dj ,precambrian of3 #dj ,silurian of3 #dj ,endopachys3 #ec ,enoploclytia3 #gi entelodont3 #aja1 #ajf ,eohippus4 ,see ,hyracotherium4 epoch1 geologic3 #cc era1 geologic3 #cc-cd ,erath ,county3 #bj ,eryops3 #ib ,euomphalus3 #fa ,euphemites3 #fb ,europe3 #hi ,exogyra arietina3 #gj laeviscula3 #gj ponderosa3 #gj texana3 #gj ,f 8false fossils03 #ad family1 taxonomic3 #bb 8feather stars03 #hb ferns3 #dg1 #dh fish3 #hg1 #hh1 #hi armored3 #da1 #hh carbon residue3 #i scales3 #aj teeth3 #aj vertebrae3 #aj ,fistulipora3 #ee ,flabellum3 #ec foramen1 pedicle3 #ed1 #ef ,foraminifera3 #dg1 #di ,cretaceous3 #di fusulinids3 #bf1 #bi1 #di orbitoid3 #bf1 #bh ,pennsylvanian3 #di forams3 #bf1 #bh1 #bi1 #dg1 #di formation1 geologic3 #cd fossil-- birds3 #e1 #ajj burrows3 #ad cataloging3 #ca collecting3 #ag equipment3 #ag ethics3 #bj how to collect3 #bj where to look3 #ai definition3 #c dung3 #ad footprints3 #ad gizzard stone3 #ad identification3 #ba1 #bc-cj keys3 #bf-cj preservation-- altered hard parts3 #aj-aa carbonization3 #i1 #aj mineralization3 #aj permineralization3 #aj petrifaction3 #aj replacement1 calcareous1 iron1 siliceous3 #aj1 #aa1 #ac kinds of3 #g original hard and soft parts3 #g record1 missing pages in3 #e wood3 #dg fossilization1 requirements of3 #e fossils-- animal3 #dg-ajg ,cambrian3 #dj carbonized3 #aj classification of3 #ba-bb cleaning3 #ba etching in acid3 #ba frozen3 #e1 #g1 #ajd guide and_/or index3 #cb in amber3 #g in oil saturated soil3 #g in quicksand3 #e in tar3 #e in volcanic ash3 #e main types of3 #dd natural mummies3 #g permineralized or petrified3 #aj plant3 #d1 #aj1 #bj1 #cb1 #dd-dh ,pleistocene3 #aja1 #ajb1 #ajc1 #ajd ,precambrian3 #dj preparation of3 #ba ,quaternary3 #dc1 #aja1 #ajb1 #ajc1 #ajd replaced or mineralized3 #aj silicified3 #ba ,cretaceous3 #aa ,permian3 #aa etching3 #ba ,silurian3 #dj1 #ha ,tertiary3 #dc ,triassic3 #db uses of3 #ca-cb ,france3 #ajf ,franklin ,mountains1 ,cambrian of3 #dj frogs3 #hi ,frondicularia3 #di fungi3 #dd ,fusselman limestone3 #dj ,fusulina3 #di fusulinids3 #bf1 #bi1 #dg1 #di ,fusus3 #fc ,g ,gaptank formation3 #ce1 #da gastroliths3 #ad ,gastropoda3 #ef1 #ei gastropods3 #bf1 #bg1 #bi1 #cj1 #ef1 #ei1 #fj ,cretaceous3 #ei1 #fb morphology3 #fj ornamentation3 #ei ,pennsylvanian3 #fa1 #fb ,tertiary3 #ei1 #fc1 #fd generic name3 #ba-bb genus3 #ba-bb geologic-- column3 #cc history3 #cc map1 definition3 #dj map of ,texas3 #ch-ci time3 #cd time scale3 frontispiece1 #cc geology of ,texas3 #cg-dc ,germany3 #e1 #ajj ,gingko3 #dg1 #dh ,girtyocoelia3 #ej ,glasscock ,county3 #db ,glass ,mountains3 #aa1 #ab1 #ce1 #da1 #db glauconite3 #aa ,globigerina3 #di ,glossary3 #aaa-aad ,glycymeris3 #gd ,glyptodon3 #aja1 #ajb glyptodont3 #aja1 #ajb goats3 #ajf goniatites3 #ge1 #gf ,grand ,prairie3 #cf1 #cg ,graptolithina3 #hd1 #hf graptolites3 #bg1 #cj1 #dj1 #hd1 #hf of ,marathon uplift3 #dj1 #hf ,graptozoa4 ,see graptolites4 graysonana1 ,gryphaea3 #fi ,great ,flood3 #c ground sloths3 #g1 #aja1 #ajb ,gryphaea graysonana3 #fi washitaensis3 #fi ,guadalupe ,mountains1 ,peak3 #ce ,gulf ,coast3 #cb ,gulf ,coastal ,plain of ,texas3 #ce1 #cf1 #cg1 #db1 #dc1 #ajf ,gulf of ,mexico3 #cg ,gulf series of ,cretaceous3 #cd4 ,see also ,upper ,cretaceous4 ,gyrodes3 #fb ,h hagfish3 #hg hammer1 geologist's3 #ag1 #ah ,hamulus3 #gh hand lens3 #ag1 #ah hard parts1 animal--calcareous1 chitinous1 phosphatic1 siliceous remains3 #aj ,hardin-,simmons ,university3 #bg heart urchins3 #hb1 #hc ,heliospongia3 #ej hematite3 #aa ,hemiaster3 #he ,hemichordata3 #hd ,henderson ,county ,junior ,college3 #bg ,herodotus3 #c ,heterostegina3 #cb ,heteralosia hystricula3 #ab1 #ac 8het0 zone3 #cb ,hexacoralla3 #ea ,high ,plains3 #ce1 #cf1 #cg1 #db1 #dc1 #hi1 #ie1 #ajf hippopotamuses3 #ajf ,holaster3 #he ,holectypus3 #he ,holothuroidea3 #hb holothuroids3 #hd sclerites3 #hc ,homo sapiens3 #bb 8horn corals03 #di1 #ea1 #eb horses3 #ajc1 #ajd teeth3 #ajd ,howard ,county ,junior ,college3 #bg ,hudspeth ,county3 #ce1 #da1 #db ,hueco ,mountains3 #da ,hughes1 ,jack ,t43 #a hydroids3 #di ,hydrozoa3 #di1 #hd ,hyracotherium3 #ajc1 #ajd hystricula1 ,heteralosia3 #ab1 #ac ,i ichthyosaurs3 #ia1 #ic1 #ie ,ichthyosaurus3 #ia1 #ic identification keys1 fossil3 #bf-cj use of3 #bc-bg igneous rocks3 #e1 #ai ,inarticulata3 #ed1 #ef ,inoceramus3 #fi insects3 #g1 #gh1 #gi in amber3 #g iron1 replacement by3 #aa ,italy3 #c ,j ,jack ,county3 #bj jellyfish3 #e1 #di ,jurassic-- derivation and pronunciation3 #cd fossils3 #db birds3 #ajj dinosaurs3 #ij1 #ia1 #ie1 #ig1 #ih1 #ii ,gingko3 #dh of ,hudspeth ,county and_/or ,malone ,mountain3 #da ,juresania3 #eh ,k keys4 ,see identification keys4 ,kilgore ,college3 #bg ,kingena wacoensis3 #ef ,l labels1 paper3 #ai laeviscula1 ,exogyra3 #gj ,lamar ,state ,college of ,technology3 #a1 #b1 #bg lampreys3 #hg ,latirus3 #fc ,lee ,college3 #bg ,lepidodendron3 #df ,levifusus3 #fd ,lima3 #gb limonite3 #aa ,lingula3 #ee1 #ef ,linnaeus3 #ba ,linn3 #ba ,linoproductus3 #eg lisbonensis1 ,ostrea3 #gb liverworts3 #dd lizards3 #hi ,llano uplift3 #cf1 #cg1 #dj1 #da ,lonsdale1 ,john ,t43 #a lophophore1 brachiopod3 #ed ,lophophyllidium3 #di1 #ea1 #eb proliferum3 #eb radicosum3 #eb ,los ,angeles1 ,california3 #e ,louisiana3 #cg ,lower ,cretaceous3 #cd1 #db1 #ef1 #ig4 ,see also ,comanchean4 lugubris1 ,alectryonia3 #fh ,lunatia3 #fb lungfishes3 #hg ,m ,macon1 ,j4 ,w43 #b magnifying glass3 #ag1 #ah ,malone ,mountain3 #db ,mammalia3 #hi1 #ajj-ajg mammoths3 #ajb1 #ajd1 #ajg frozen3 #g1 #ajb tooth3 #ajd woolly3 #ajb1 #ajd1 #ajg mantle1 brachiopod3 #ed pelecypod3 #ei maps-- county3 #ag geologic3 #ai of ,texas3 #ch-ci physiographic of ,texas3 #cf topographic3 #ai1 #bj ,marathon uplift3 #ce1 #cf1 #dj1 #da marcasite3 #aa ,marginifera3 #eg opima3 #ab1 #ac mastodon1 tooth3 #ajd ,meandrostia3 #ej ,mediterranean ,sea3 #c mercenaria1 ,venus3 #bb ,mesalia3 #fc ,mesolobus3 #eg ,mesozoic-- derivation and pronunciation3 #cc periods of3 #cd rocks in ,texas3 #db-dc metamorphic rocks3 #e1 #ai ,metoicoceras3 #gf ,michelinia3 #eb ,micrabacia3 #di1 #eb microfossils3 #d1 #aj1 #cb1 #dg1 #di1 #ej1 #gh micropaleontological slides3 #cb micropaleontologist3 #cb1 #dg1 #hj micropaleontology3 #d1 #hi ,midwestern ,university3 #bg mine dumps3 #bj1 #dg ,mississippian-- derivation and pronunciation3 #cd fossils3 #da blastoid3 #ha brachiopods3 #ee bryozoan3 #ed of ,hueco ,mountains3 #da of ,llano region3 #da mold1 external3 #i1 #aa1 #ei1 #ff internal3 #i1 #aa1 #ei1 #fb1 #ff ,mollusca3 #ef-gh mollusks3 #g1 #ef1 #ei-gh4 ,see also ,mollusca4 ,moropus3 #ajf mosasaur3 #ia1 #ic1 #ie 8moss animals03 #ed mosses3 #dd ,muirwoodia multistriatus3 #ab1 #ac multituberculates3 #ajj multistriatus1 ,muirwoodia3 #ab1 #ac mussels3 #ef1 #ei museums1 as aid in identification3 #bc ,american1 ,natural ,history3 #b1 #ae1 #if ,strecker3 #ie ,texas ,memorial3 #ad1 #hg1 #ie1 #ig1 #ajj1 #ajb ,myalina3 #fg ,mylodon3 #ajj1 #aja ,n ,nautiloidea3 #ff nautiloids3 #ff ,cretaceous3 #gf morphology3 #ge ,pennsylvanian3 #gf sutures3 #ge ,nautilus3 #ff morphology3 #ge ,neithea3 #gj ,neospirifer3 #eg cameratus3 #eh ,nerinea3 #fb ,neuropteris3 #dh ,neverita3 #fd ,new ,mexico3 #g ,new ,york ,city3 #ad ,north-,central ,plains3 #ce1 #cf1 #cg1 #dj1 #da1 #db1 #dc north ,texas3 #db ,north ,texas ,state ,college3 #bg notebook1 field3 #ag ,notopocorystes3 #gi1 #hj ,nucula3 #gc ,nuculana3 #fg ,nuculopsis3 #fg ,o octopus3 #ff1 #gh ,odessa ,college3 #bg operculum3 #ei ,ophiuroidea3 #hb ophiuroids3 #hb opima1 8,marginifera03 #ab1 #ac order1 taxonomic3 #bb ,ordovician-- derivation and pronunciation3 #cd fossils3 #dj graptolites3 #hf of ,el ,paso region1 ,llano1 ,marathon1 ,solitario1 and ,van ,horn uplifts3 #dj ornamentation1 brachiopod3 #ed gastropod3 #ei pelecypod3 #ff ,ornithischia3 #ig ornithischians3 #ij1 #ig1 #ih1 #ajj ,ornithopoda3 #ig ornithopods3 #ij1 #ig1 #ii ,orthoceras3 #ff1 #gf ,orthoyoldia3 #gc ossicles4 ,see sclerites4 ,osteichthyes3 #hg ,ostracoda3 #hj ostracoderms3 #hg ostracodes3 #gh1 #gi1 #hj ,ostrea carinata3 #ga lisbonensis3 #gb quadriplicata3 #ga sellaeformis3 #gb ,oxytropidoceras3 #gg oysters3 #ef1 #ei ,p ,pachecoa3 #gb ,pachymya3 #ga paleobotany3 #d paleobotanists3 #dd paleontology-- definition3 #d divisions of3 #d history of3 #c invertebrate3 #d vertebrate3 #d ,paleoscincus3 #ij1 #ig1 #ii1 #ajj ,paleozoic-- derivation and pronunciation3 #cc periods of3 #cd rocks of ,texas3 #dj-db ,palo ,pinto ,county3 #bj ,paluxy ,creek3 #ad1 #ae ,pan ,american ,college3 #bg ,pantodonta3 #ajb pantodonts3 #ajb ,parasaurolophus3 #ij ,parasmilia3 #ec ,parker ,county3 #bj ,pawpaw formation3 #aa pearly nautilus3 #ff morphology3 #ge ,pecos ,county3 #db ,pecos ,river valley3 #ce ,pecten3 #ei1 #fh1 #gd pedicle3 #ed1 #ef foramen3 #ed1 #ef valve1 brachiopod3 #ed ,pelycosaurs3 #hi1 #ib ,pelecypoda3 #ef1 #ei1 #fe-ff pelecypods3 #bf1 #bi1 #cj1 #ef1 #ei1 #fj1 #ff ,cretaceous3 #ei1 #ff1 #fh-ga dentition3 #ff morphology3 #ei1 #fj1 #fe1 #ff ornamentation3 #ff ,pennsylvanian3 #ff1 #fg teeth3 #fj1 #fe1 #ff ,tertiary3 #gb1 #gc1 #gd ,pelmatozoa3 #hj1 #ha ,pennsylvanian-- derivation and pronunciation3 #cd fossils3 #da brachiopods3 #eg1 #eh bryozoans3 #ee cephalopods3 #ff1 #gf corals3 #eb crinoids3 #da1 #hb1 #hc fusulinids3 #dg1 #di gastropods3 #fa1 #fb nautiloids3 #gf pelecypods3 #ff1 #fg plants3 #df1 #dg1 #dh shark teeth3 #hg sponges3 #ej of ,diablo and ,hueco ,mountains1 ,llano and ,marathon uplifts1 and north-central ,texas3 #da ,pentaceros3 #hc ,pentagonaster3 #hc ,pentremites3 #ha period1 geologic3 #cc periostracum3 #fj ,perissodactyla3 #ajd perissodactyls3 #ajc1 #ajd1 #aje ,permian-- derivation and pronunciation3 #cd fossils3 #da amphibian3 #hi1 #ib brachiopods3 #ab1 #ac cotylosaurs3 #hi1 #ib pelycosaurs3 #hi1 #ib of ,glass ,mountains3 #aa1 #ab1 #ce permiana1 ,prorichthofenia3 #ab1 #ac permineralized bone3 #i petroleum geologist3 #d ,phaneroceras3 #gf ,phobosuchus3 #ie1 #if ,pholadomya3 #ga1 #gb phyla3 #bb ,phyllograptus3 #hf phylum3 #bb physiographic provinces1 of ,texas3 #ce-cg physiography1 definition3 #ce of ,texas3 #ce-cg phytosaurs3 #db1 #ia1 #id1 #ie pick1 mineralogist's or prospector's3 #ag1 #ah pigs3 #ajf ,pinna3 #fg ,pisces3 #hf-hi ,pitar3 #gb ,placodermi3 #hg placoderms3 #hg1 #hh plant kingdom3 #dd plants1 classification3 #dd ,pennsylvanian3 #df1 #dg1 #dh ,platyceras3 #fb ,pleistocene3 #dc4 ,see also ,quaternary4 fossils3 #aja1 #ajb1 #ajc1 #ajd plesiosaurs3 #ia1 #ic1 #ie ,pleurocora3 #ec ,plicatula3 #fh1 #gd ,pliohippus3 #ajc ,poland3 #g1 #ajf pollen3 #dg polyp1 coral3 #di ,polypora3 #ee ponderosa1 ,exogyra3 #gj ,porifera3 #di ,porodiscus3 #di portland cement3 #ai ,precambrian-- definition3 #cd fossils3 #dj of ,el ,paso region3 #dj of ,llano uplift3 #cg1 #dj of ,van ,horn uplift3 #dj rocks of ,texas3 #dj ,presidio ,county3 #ce ,proboscidea3 #ajb proboscideans3 #ajb1 #ajd1 #ajg teeth3 #ajd proliferum1 ,lophophyllidium3 #eb ,prorichthofenia permiana3 #ab1 #ac ,proterozoic1 derivation and pronunciation3 #cc ,protista3 #dg ,protocardia3 #fh ,protoceratops3 #ij ,protozoa3 #dg1 #di protozoans3 #dg pseudofossils3 #ad ,pseudoliva3 #fc ,psilophyton3 #dh ,pteranodon3 #ia1 #id ,pterodactyloids3 #ia pterosaurs3 #ia1 #id1 #ie ,punctospirifer3 #eg pyrite3 #aa 8,pyrite ,fossil ,zone0 of ,cretaceous3 #aa ,q quadriplicata1 ,ostrea3 #ga quarries3 #ai ,quaternary-- derivation and pronunciation3 #cd fossils3 #dc1 #aja1 #ajb1 #ajc1 #ajd of ,edwards ,plateau1 ,gulf ,coast1 ,high ,plains1 ,north-,central ,plains1 and ,trans-,pecos ,texas3 #dc quicksand3 #e ,r radicosum1 ,lophophyllidium3 #ec ,radiolaria3 #dg radiolarians3 #dg1 #di ,rancho ,la ,brea tar pit3 #e rays3 #hg ,reagan ,county3 #db ,receptaculites3 #ej ,renaissance3 #c ,reptilia3 #hi-ajj reptiles3 #hi-ajj rhamphorhynchoids3 #ia ,rhamphorhynchus3 #ia1 #id rhinoceroses3 #g1 #ajd1 #ajf1 #ajg woolly3 #ajf1 #ajg ,rhipodomella3 #ee ,rhombopora3 #ea1 #ee ,rice ,university3 #bg ,rio ,grande valley1 of ,trans-,pecos3 #ce1 #ie road metal3 #ai ,robulus3 #di ,rock and ,mineral ,clubs3 #bc rock units3 #cd rockymontanus1 ,spirifer3 #eh ,rodda1 ,peter ,u43 #a rudistids3 #bf1 #bg1 #bh1 #bi1 #cj ,rugosa3 #ea ,s saber-tooth cat3 #ajb1 #ajc ,st4 ,mary's ,university3 #bg salamanders3 #hi ,salenia3 #he ,san ,angelo ,college3 #bg ,san ,antonio ,college3 #bg sand dollars3 #hb sapiens1 ,homo3 #bb ,sarcodina3 #dg ,saurischia3 #ig saurischians3 #ij1 #ig1 #ii ,sauropoda3 #ig sauropods3 #ij1 #ig1 #ih scale trees3 #df1 #dg scallops3 #ef1 #ei ,scaphopoda3 #ef scaphopods3 #bf1 #bg1 #bh1 #bi1 #ef ,schizodus3 #fg scientific names3 #ba-bc ,scleractinia3 #ea sclerites1 holothurian3 #hc1 #hd scolecodont3 #gh scouring rushes3 #dg1 #dh ,scyphozoa3 #di1 #hd sea anemones3 #di sea cucumbers3 #hb 8sea lily03 #ha1 #hb 8sea mats03 #ea1 #ed 8sea-mice03 #ef sea urchins3 #hb sedimentary rocks3 #e1 #ai sellaeformis1 ,ostrea3 #gb septa1 cephalopods3 #ff1 #ge corals3 #di1 #ea serpent stars3 #hb ,serpula3 #gh ,seymouria3 #ib sharks3 #hg teeth3 #aj1 #hg1 #hh sheep3 #ajf shrimp3 #gh ,siberia3 #g1 #ajf ,sigillaria3 #df signata1 ,avonia3 #ab1 #ac silica3 #aj1 #aa silicification3 #aa ,silurian-- derivation and pronunciation3 #cd fossils3 #dj cystoid3 #ha of ,el ,paso and ,van ,horn regions3 #dj skates3 #hg slickensides3 #af slugs3 #ef ,smith1 ,fred3 #a snails3 #aa1 #ef1 #ei4 ,see also gastropods4 snakes3 #hi ,solitario uplift3 #dj ,somervell ,county3 #ad1 #ae ,south ,america3 #hg1 #ajb ,southern ,methodist ,university3 #bg ,south ,texas ,college3 #bg ,southwestern ,university3 #bg species3 #bb spicules1 sponge3 #di1 #ej spiders3 #gh spines1 echinoid3 #hd1 #he ,spirifer rockymontanus3 #eh ,spirorbis3 #gh sponges3 #aj1 #bg1 #cj1 #di1 #ej spores3 #dg ,squamularia3 #eg squid3 #ff1 #gh starfish3 #hb1 #hc ,stegosaurus3 #ij1 #ig1 #ii stegosaurs3 #ij1 #ig1 #ii steinkern3 #ei1 #fb stems1 crinoid3 #bf1 #bh1 #da1 #ha1 #hb1 #hc ,stephen ,f4 ,austin ,state ,college3 #bg 8stomach stones03 #ad stone1 building3 #ai ,strabo3 #c ,straparolus3 #fa ,strecker ,museum3 #ie ,striatopora3 #ea1 #eb ,strobeus3 #fb ,styracosaurus3 #ij subhorrida1 ,avonia3 #ab1 #ac subtilita1 ,composita3 #eg ,sul ,ross ,state ,college3 #bg ,surcula3 #fd sutures1 cephalopod3 #ff1 #ge1 #gh nautiloid3 #ge swine1 giant3 #ajf ,sycostoma3 #fd symmetry3 #bc bilateral3 #bd1 #bf1 #bi radial3 #bd1 #bf1 #bh1 #hj ,t tabulae3 #ea ,tabulata3 #ea tape1 masking3 #ai tapirs3 #ajd tar3 #e ,tarleton ,state ,college3 #bg ,tarrant ,county3 #aa taxonomy3 #ba-bb teeth1 horse3 #ajd mammoth3 #ajd shark3 #aj1 #hg1 #hh ,tellina3 #gc ,tertiary-- derivation and pronunciation3 #cd fossils3 #dc corals3 #ec gastropods3 #ei1 #fc1 #fd mammals3 #ajj-ajg1 #ajc1 #aje microfossils3 #cb pelecypods3 #gb1 #gc1 #gd radiolarians3 #di rocks of ,gulf ,coastal ,plain1 ,high ,plains1 ,north-,central ,plains1 and ,trans-,pecos region3 #db ,tetracoralla3 #ea ,tetrapoda3 #hf1 #hi-ajg texana1 ,exogyra3 #gj ,texanites3 #gg ,texas ,a4 ,m4 ,college3 #a1 #bg ,texas ,christian ,university3 #bg ,texas ,college3 #bg ,texas ,college of ,arts and ,industries3 #bg ,texas ,highway ,department3 #ag ,texas ,memorial ,museum3 #ad1 #hg1 #ie1 #ig1 #ajj1 #ajb ,texas ,technological ,college3 #bg ,texas1 the geology of3 #cd1 #cg-dc ,texas ,western ,college3 #bg ,thallophyta3 #dc1 #df ,theophrastus3 #c ,therapsids3 #hi ,theria3 #ajj therians3 #ajj-ajg artiodactyls3 #aja1 #ajf carnivores3 #ajb1 #ajc dinocerates3 #ajb1 #aje edentates3 #ajj1 #aja1 #ajb pantodonts3 #ajb perissodactyls3 #ajd proboscideans3 #ajb1 #ajd1 #ajg ,theropoda3 #ig theropods3 #ij1 #ig1 #ih ,the ,university of ,texas3 #a1 #b1 #bg time1 geologic3 #cd titanotheres3 #ajd1 #aje1 #ajf toads3 #hi tortoises3 #hi traces of organisms3 #ad burrows3 #ad coprolites3 #ad gastroliths3 #ad tracks3 #ad1 #ae trails3 #ad ,tracheophyta3 #dd1 #df1 #dh ,trachodon3 #ij1 #ig1 #ii tracks1 dinosaur3 #ad1 #ae1 #ig ,trans-,pecos region3 #ce1 #cf1 #dj1 #db1 #dc1 #hf1 #ie1 #ajb1 #ajf tree sloths3 #ajj1 #ajb trees1 coniferous3 #g ,trepospira3 #fa ,triassic-- derivation and pronunciation3 #cd fossils3 #db dinosaurs3 #ie phytosaurs3 #ia1 #id1 #ie of ,crockett1 ,glasscock1 ,pecos1 ,reagan1 and ,upton counties2 ,glass ,mountains and ,high ,plains3 #db ,triceratops3 #ij1 #ii1 #ajj ,trigonia3 #fi ,trilobita3 #gh trilobites3 #gh1 #hj morphology3 #hj ,trilobitomorpha3 #gh ,trinacromerum3 #ia ,trinity ,university3 #bg trivial name3 #ba-bb ,trochosmilia3 #ec ,tuba3 #fd tuberculatus1 ,aulosteges3 #ab1 #ac ,turrilites3 #gg worthensis3 #bb ,turritella3 #fb1 #fc turtles3 #hi1 #ia tusk-shells3 #ef ,tyler ,junior ,college3 #bg ,tylosaurus3 #ia1 #ic ,tylostoma3 #fb ,tyrannosaurus3 #ij1 #ig ,u uintatheres3 #ajb1 #aje ,uintatherium3 #ajb1 #aje umbilicus3 #ei1 #fj ,united ,states ,geological ,survey3 #ai ,united ,states ,national ,museum3 #b1 #ab ,university of ,corpus ,christi3 #bg ,university of ,houston3 #a1 #bg ,university of ,texas1 ,the3 #a1 #b1 #bg ,upper ,cretaceous3 #cd1 #db1 #gh4 ,see also ,gulf4 ,upton ,county3 #db ,v valves1 brachiopod3 #ed1 #ef pelecypod3 #ei1 #fe1 #ff ,van ,horn uplift3 #ce1 #cf1 #dj1 #da ,venericardia3 #gc bulla3 #gb ventral valve1 brachiopod3 #ed ,venus mercenaria3 #bb ,vertagus3 #fc ,vertebrata3 #hd1 #hf-ajg vertebrates3 #hf-ajg amphibians3 #hi1 #ib birds3 #ajj fish3 #hg1 #hh1 #hi mammals3 #ajj-ajg reptiles3 #hi-ajj ,vokesula3 #gc volcanic ash3 #e ,volutolithes3 #fd ,w ,waco3 #ia1 #ib1 #ie wacoensis1 ,kingena3 #ef ,washington1 ,d4 ,c43 #ai washitaensis1 ,gryphaea3 #fi ,weches formation3 #dc ,west ,texas ,state ,college3 #a1 #bg ,wilson1 ,john ,a43 #b ,wilson1 ,sarah ,louise3 #b ,wise ,county3 #bj wood1 petrified3 #ai ,woodbine3 #aj1 #cg1 #dg worms1 annelid1 fossil1 segmented3 #gh worm tubes1 ,cretaceous3 #i ,worthenia3 #fa worthensis1 ,turrilites3 #bb ,y ,yoldia3 #fg ,young ,county3 #bj ,young1 ,keith3 #a ,z ,zoantharia3 #ea zooecia3 #ea ,transcriber's ,notes --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,corrected a few palpable typos4 --,included a transcription of the text within some images4 --,in the text versions only1 text in italics is delimited by underscores4