,illustration3 ,department of the ,interior ,march #c1 #ahdi ,,united ,,states ,,department ,,of ,,the ,,interior ,fred ,a4 ,seaton1 ,secretary ,,national ,,park ,,service ,conrad ,l4 ,wirth1 ,director ,for sale by the ,superintendent of ,documents1 ,u4 ,s4 ,government ,printing ,office ,washington #be1 ,d4 ,c4 ,price #be cents ,,the ,,dinosaur ,,quarry ,,dinosaur ,,national ,,monument ,colorado ,utah ,by ,john ,m4 ,good1 ,theodore ,e4 ,white and ,gilbert ,f4 ,stucker ,illustration3 ,apatosaur in ,swamp ,,national ,,park ,,service ,washington1 ,d4 ,c41 #aieh ,the ,national ,park ,system1 of which ,dinosaur ,national ,monument is a unit1 is dedicated to conserving the scenic1 scientific1 and historic heritage of the ,united ,states for the benefit and enjoyment of its people4 ,illustration3 ,national ,park ,service ,department of the ,interior ,contents ,page ,,the ,,quarry #b ,,the ,,dinosaurs #c ,first ,discoveries #c ,position of ,dinosaurs ,among ,reptiles #d ,geologic ,history #d ,what ,they ,looked ,like #f ,temperature ,tolerance #aj ,gizzard ,stones #aa ,,the ,,climate1 ,,life1 ,,and ,,landscape ,,of ,,jurassic ,,time #ab ,how ,do ,we ,know8 #ad ,,animals ,,from ,,the ,,quarry #ae ,why ,so ,many8 #ai ,how ,were ,they ,preserved8 #ba ,how ,were ,they ,exposed8 #bd ,,why ,,did ,,dinosaurs ,,become ,,extinct8 #be ,,history ,,and ,,development ,,of ,,the ,,quarry #bf ,discovery and ,early ,years #bf ,starting the ,quarry #bh ,extent and ,development of the ,find #bh ,work ,methods #cb ,further ,development #cd ,protecting the ,quarry #ce ,present ,development #cg ,,the ,,scene ,,today #ch ,,key ,,to ,,pronunciation #df ,,suggested ,,readings #dg ,illustration3 ,,jurassic ,,landscape ,,showing ,,animals ,,and ,,plants ,,that ,,lived ,,here ,,during ,,morrison ,,time4 7,,from ,a ,,painting ,,by ,,ernest ,,unterman47 ,illustration3 ,spade and ,pick ,as you approach ,dinosaur ,national ,monument from ,jensen1 ,utah1 you see the mass of ,split ,mountain and the deep1 short canyons that scar its south slope near the ,green ,river's gorge4 ,as you cross the ,national ,monument boundary the grand view is lost and you begin to notice details4 ,the masses of gray shale that seem to be carelessly piled against the tilted sandstone layers are bare of vegetation4 ,the ground between the hills and the ,green ,river is covered with sagebrush and greasewood1 while along the river itself are a few large cottonwood trees and many bushes4 ,a sharp turn brings a change of scene as your car enters a portal in the wall you have been following4 ,the pronounced tilt of the rocks becomes more obvious4 ,a final steep climb and the visitor center is at hand4 ,this building encloses a significant part of the ,dinosaur ,quarry1 perhaps the greatest deposit of fossil dinosaur bones known today4 ,from this quarry have come many of the dinosaur skeletons that are seen today in our great museums4 ,after parking1 a short walk to the overlook on the southeast reveals a splendid view of ,split ,mountain4 ,between that broad arch of eroded sandstone and the quarry lie steeply tilted sedimentary rocks of various compositions and hues4 ,buff and gray sandstones that weather into soft shapes are separated by reddish-brown shale4 ,directly to the east is a section of varicolored shale whose pastel pinks1 reds1 greens1 grays1 and whites justify the name of 8rainbow beds0 that was given them by geologists4 ,in the upper part of this section are hard sandstone and limestone layers that resist the erosive action of wind and water4 ,they stand higher than the softer shales and form hogbacks that rim ,split ,mountain4 ,one of these layers can be traced across the ravine immediately east of the parking area into the sandstone ledge that forms the north wall of the visitor center4 ,this is the famous ,dinosaur ,ledge4 ,the ,quarry ,the ,dinosaur ,ledge is famous because here the world's greatest store of fossil bones of these long extinct reptiles has been uncovered4 ,two groups1 or orders1 of dinosaurs have been discovered1 with a number of different types or kinds somewhat related to each other within these orders4 ,from the fossil bones1 scientists can tell that these creatures varied greatly in size and habits of living4 ,illustration3 ,,tilted ,,rock ,,strata ,,near ,,the ,,dinosaur ,,quarry4 ,some were the size of chickens1 others as big as horses1 and others of such gigantic size that no land animal alive today can compare with them4 ,some were flesh-eaters as indicated by the size and shape of their teeth and their long sharp claws4 ,others were plant-eaters and again it is the structure of their teeth and feet that tell us this4 ,the flesh-eaters were two-footed and walked on their hind legs1 balancing themselves with heavy long tails4 ,their short front legs were used as clawed-arms for tearing at the flesh of other dinosaurs4 ,many plant-eaters1 on the contrary1 were large1 heavy1 four-footed beasts1 often with long necks and tails4 ,many of the dinosaurs were land dwellers1 and many others lived in the great marshes and swamps of the long ,mesozoic 7middle life7 ,era of the earth's history4 ,though the subclass of reptiles we call dinosaurs lived all through the ,mesozoic ,era1 those whose fossil bones have been uncovered in this ,dinosaur ,quarry are embedded in a stratum of rock called the ,morrison formation4 ,this rock stratum dates from the ,jurassic ,period in the middle of the ,mesozoic ,era4 ,the ,dinosaurs ,,first ,,discoveries ,today1 most of us would recognize a fossil bone for what it is1 but in the #agij's things were different4 ,isolated legbones1 vertebrae1 and teeth of huge reptiles had been dug out of certain sedimentary rocks of ,europe and ,north ,america but their scientific importance was little understood4 ,these specimens were found by people in all walks of life and it was natural that their curiosity was greatly aroused4 ,the finders took the specimens to someone nearby whom they considered more competent to tell them something about these strange bones and teeth4 ,in nearly all cases these 8experts0 were doctors of medicine4 ,they studied the fossil specimens and reported on them at regular meetings of the learned societies of which they were members4 ,it was customary to put the fossils in the collections of these societies where they could be studied by other members4 ,in ,north ,america most reports of these early discoveries are found in the ,proceedings of the ,american ,philosophical ,society in ,philadelphia1 ,pa4 ,by #ahdb accumulated knowledge of these large reptiles was sufficient to show that they were distinct from any group then known4 ,this was first recognized by ,sir ,richard ,owen of the ,british ,museum4 ,it was he who named the group ,dinosauria4 ,the name is made up of two ,greek words3 deinos 7terrible7 plus sauras 7lizard74 ,as knowledge of these unusual reptiles increased through the discovery of additional types and more complete and better preserved specimens1 it became evident that dinosaurs were neither a single group of reptiles nor were all of them large4 ,actually the dinosaurs show as much diversity in size1 body form1 and habits as any group of reptiles4 ,the smallest dinosaur walked on its #b hind legs like a chicken and was about the same size4 ,the largest walked on all #d legs1 was about #hj feet long1 and weighed #cj to #dj tons4 ,as examples of variety in body form there are the two-footed1 flesh-eating ,antrodemus1 the armored ,stegosaurus1 the turtle-like ,ankylosaurus1 the horned ,triceratops1 the huge ,apatosaurus1 the two-footed vegetarian ,camptosaurus1 and the great variety of head forms in the aquatic hadrosaurs4 ,although there were two distinct groups1 we still retain the term 8dinosaur0 as a convenient name for all of them but qualify it by saying1 flesh-eating dinosaur1 plant-eating dinosaur1 armored dinosaur1 etc41 to indicate the particular type we are talking about4 ,perhaps you are wondering how all these ancient creatures are related to reptiles in general4 ,where do they fit in the classification system devised to bring order to this mass of knowledge8 ,,position ,,of ,,dinosaurs ,,among ,,reptiles ,it seems there are several orders of reptiles similar to and closely related to the dinosaurs4 ,remains of these reptiles are found in the sedimentary rocks which contain the earliest known dinosaurs4 ,a number of them resembled the dinosaurs but do not quite meet the requirements as far as details of the skeleton are concerned4 ,in the scheme of classification these orders of reptiles are grouped together into the subclass ,archosauria4 ,this subclass includes the dinosaurs1 crocodiles1 and the flying reptiles4 ,the lizards1 snakes1 turtles1 and the tuatera of ,new ,zealand belong to other subclasses of reptiles which have been distinct from that of the dinosaurs as far back in geologic time as we can trace them4 ,the kinship between the dinosaurs and the small lizards living in the monument today lies only in that both are reptiles4 ,the only living relatives of the dinosaurs are the alligator and the crocodile4 ,the dinosaurs were so numerous1 and so dominated the whole of the ,mesozoic ,era1 that this period of earth history is frequently referred to as the ,age of ,reptiles4 ,,geologic ,,history ,the ,mesozoic ,era began some #bjj million years ago and ended some #fj million years ago4 ,although many other animals lived during that era1 the dinosaurs were the dominant forms of animal life on land4 ,the #adj million years of the ,mesozoic are divided into geologic periods named ,triassic 7the oldest71 ,jurassic1 and ,cretaceous 7the most recent74 ,continental deposits representing each of these periods have been found in all parts of the world and on all continents4 ,dinosaur bones have been found in these deposits--even in such far-away places as ,australia and the southern tip of ,south ,america4 ,only ,jurassic dinosaurs have been found at ,dinosaur ,national ,monument4 ,illustration3 ,coelophysis--,,small ,,triassic ,,dinosaurs1 ,,forerunners ,,of ,,the ,,huge ,,dinosaurs ,,of ,,jurassic ,,period4 7,,drawn ,,by ,,margaret ,m4 ,,colbert4 ,,courtesy1 ,,american ,,museum ,,of ,,natural ,,history47 ,the oldest known dinosaurs are found in rocks of the ,triassic ,period4 ,the smaller of these were chicken-size and the largest were about as big as kangaroos4 ,all of these ,triassic dinosaurs were two-footed4 ,they can be divided into flesh-eaters and plant-eaters1 although none are believed to have been particularly specialized in their food habits4 ,in general the flesh-eaters were small1 agile1 and had sharp teeth for seizing and overpowering active prey4 ,the plant-eaters were larger with rather long front legs and small blunt teeth suited only to cropping vegetation4 ,these plant-eaters are believed to be the ,triassic ancestors of the giant marsh-dwelling dinosaurs of the ,jurassic and ,cretaceous ,periods4 ,a greater variety of dinosaurs lived during the ,jurassic ,period than in the ,triassic4 ,both two- and four-footed types were present4 ,the flesh-eaters remained two-footed but increased in size4 ,antrodemus1 perhaps the best known1 was much bigger than a kangaroo4 ,the larger plant-eaters weighed from #cj to #dj tons and all were four-footed4 ,the largest land animals1 they lived on dry land and in the swamps that formed an important part of the ,jurassic landscape4 ,the first of the armored plant-eating dinosaurs1 ,stegosaurus1 inhabited the dry plains4 ,there were also some smaller1 kangaroo-size plant-eaters that were two-footed4 ,a wide variety of dinosaur fossils has been found in the rocks of the ,cretaceous ,period1 the last of the ,mesozoic ,era4 ,the huge swamp dwellers still thrived4 ,the flesh-eaters had evolved much larger types and included #dj-;foot ,tyrannosaurus1 the largest that ever lived4 ,all the flesh-eaters walked on their hind legs as did their predecessors of the ,jurassic and ,triassic ,periods4 ,new and interesting dinosaurs were present among the flesh-eaters4 ,horned forms1 somewhat similar to the rhinoceros but much larger1 were common4 ,also common were the turtle-like ankylosaurs4 ,perhaps the oddest and most interesting dinosaurs of the ,cretaceous were the two-footed hadrosaurs4 ,these excellent swimmers had weird head shapes with complicated skull passages and openings4 ,they were a very successful group and at least #ae different kinds are known from the ,cretaceous rocks of ,north ,america4 ,,what ,,they ,,looked ,,like ,ideas about the external appearances of dinosaurs have been developed after many years of work and study4 ,they are a combination of the ideas of several people who had studied different specimens of a single species4 ,let us review briefly the materials and work necessary to arrive at a reasonably accurate picture of the body form and external appearance of these strange reptiles4 ,the first requirement for arriving at a good idea of the build and physical attitude of an animal is a nearly entire skeleton4 ,we cannot have too much of the animal's skeleton missing or we may make a serious error4 ,but if the left hind leg is missing and we have the right1 we are not seriously handicapped4 ,however1 if both hind legs are missing we must restore them according to a similar animal whose hind legs are known4 ,after the nearly entire skeleton has been found it must be collected with great care4 ,this is a rather involved process and1 for some of the large dinosaurs1 #b or #c months work may be required4 ,the specimen is first uncovered and the fossil bone is treated with a preservative such as gum arabic1 shellac1 or one of the plastics4 ,an accurate diagram of the specimen as it lies in the rock is made on cross-ruled paper4 ,a trench #b or #c feet wide is then dug around the specimen4 ,the depth of the trench is determined by the width of the specimen and the nature of the rock4 ,illustration3 ,,putting ,,plaster ,,cast ,,on ,a ,,fossil ,,before ,,removing ,,it ,,from ,,the ,,quarry4 ,if the specimen is too large to take out in one piece1 as most dinosaurs are1 it is divided into sections which are numbered serially as they are taken out4 ,each section is bandaged in strips of burlap dipped in plaster of ,paris4 ,after the plaster has set1 the section is turned over and the bottom is sealed with burlap and plaster4 ,the section is labeled with the appropriate number and the section and number are shown on the diagram4 ,when all of the sections have been bandaged and numbered they are packed in strong wooden boxes and shipped to the laboratory4 ,the work in the laboratory is more involved than that in the field1 and extreme care must be exercised to be sure that the bones will be undamaged4 ,in most cases the bones have been broken by natural causes as they lay in the rock before discovery4 ,all the pieces of each bone must be thoroughly cleaned and securely cemented together4 ,this is a very time-consuming task and for a large dinosaur like ,apatosaurus it requires #c men #d or #e years to complete the task4 ,after all of the bones are cleaned and cemented together the vertebral column is laid out in its proper sequence on a sand table4 ,special care is exercised to be sure that the vertebrae fit correctly with each other4 ,in this way the correct curvature of the vertebral column is determined4 ,the proper relationships of the hip bones and ribs to the vertebrae1 the shoulder blade to the ribs1 and elements of the limb bones to each other are determined in the same manner4 ,all of this work is necessary to correctly fashion the steel framework which will support the skeleton when it is placed on exhibition4 ,the results of this careful work must be the framework of an animal which could1 if living1 easily go through the normal activities of life such as securing food and escaping enemies4 ,now that the framework of an animal has been set up so that it could move about if it had muscles1 skin1 and life1 how do we know how large the muscles were and where they were placed8 ,it is necessary to have a thorough knowledge of the muscles of a recent animal similar to the one we are restoring so that we will know what we are looking for in the fossil4 ,the areas at which muscles are attached to bones are called muscle scars and are identified by their rough surfaces4 ,often the necessary information can be obtained from publications which usually represent the work done by graduate students for advanced degrees4 ,at other times we must make our own investigation4 ,thus if we know what muscle we are looking for and the size and shape of its muscle scar1 we can determine whether the muscle is a spindle-shaped mass or a broad sheet4 ,after we have determined the size and position of the muscles which operate the limbs1 head1 and neck1 we have a reasonably accurate idea of the external form of the animal1 but we still know nothing of the nature of the skin which covered the body4 ,since dinosaurs were reptiles1 we are obliged to assume that they were covered with a scaly skin in order to preserve the body moisture4 ,none of the modern reptiles possess sweat glands in the skin4 ,if they did not possess a waterproof covering of scales they would die in a few hours as a result of the loss of body moisture by evaporation through the skin4 ,it is possible that some of the marsh dwellers like ,apatosaurus had naked skin which was1 as in the elephant1 nearly an inch thick4 ,the elephant does not possess sweat glands but the outer half of its skin is composed entirely of dead cells which form a covering as waterproof as the scales of today's reptiles4 ,there have been only a few lucky finds of mummified dinosaurs which show the impressions of the scales4 ,we know that all lizards do not possess the same type of scales1 and therefore1 by analogy1 we cannot assume that the dinosaurs did4 ,eventually1 we will probably find that the dinosaurs exhibited as great a variety of scale-types as do today's lizards4 ,as yet we have found nothing in the fossil record which indicates the color of the dinosaurs4 ,again1 we can only assume that they exhibited as great a variety of colors as do our lizards4 ,so also1 we assume their body functions were somewhat similar to the reptiles and other related animals we know today4 ,illustration3 ,,dinosaur ,,fossil ,,with ,,skin ,,and ,,ligaments ,,preserved4 7,,not ,,from ,,dinosaur ,,quarry4 ,,courtesy1 ,,american ,,museum ,,of ,,natural ,,history47 ,illustration3 ,,rare ,,fossil ,,of ,,dinosaur ,,skin4 7,,courtesy1 ,,american ,,museum ,,of ,,natural ,,history47 ,,temperature ,,tolerance ,we know the body temperatures of reptiles vary with that of the air or water in which they live1 as they have no means of internal temperature control4 ,they are very sluggish when their body temperatures are low and become more active as these temperatures rise1 but only to a certain point4 ,if the body temperatures of reptiles become too high1 they die in a few minutes4 ,a group of physiologists from ,columbia ,university spent nearly #b months in southern ,florida experimenting on reptiles4 ,they determined the rate of rise of body temperatures of large lizards and alligators of all sizes during exposure to the midday sun4 ,as was expected1 the smaller the reptile the more rapid the rise in body temperature4 ,dinosaurs were reptiles so we can make two assumptions3 ,that their physiology was very similar to that of living reptiles2 and that the rate of rise of their body temperatures from exposure to the sun would follow the principles found for living reptiles4 ,by applying these principles to the dinosaurs1 this group of scientists calculated that if the great bulk of an ,apatosaurus were exposed to the direct rays of the sun at an air temperature of #aaj ,f4 for #cf to #dj hours1 its body temperature would rise only #a ,f4 ,therefore1 if these calculations are correct1 it is probable that the very size of the huge dinosaurs operated to maintain a fairly constant body temperature4 ,consequently1 daily and seasonal temperature changes probably did not affect the activities of the large dinosaurs4 ,however1 the activities of the small ones may have been affected by the daily range in temperature4 ,,gizzard ,,stones ,for many years rounded stones with a very high polish have been found in the sedimentary rocks which contain bones of extinct reptiles4 ,the polish on these stones is very much higher than could have been applied by the action of water or wind4 ,some look as though they had been polished by a jeweler4 ,since we cannot attribute this very high polish to wind or water action1 we must seek another agent4 ,illustration3 ,protiguanodon4 ,,note ,,gizzard ,,stones ,,inside ,,rib ,,basket4 7,,courtesy1 ,,american ,,museum ,,of ,,natural ,,history47 ,just as chickens swallow fine gravel for their gizzards to aid digestion1 so it is thought that some large dinosaurs swallowed stones for the same purpose4 ,there is some evidence to support this idea4 ,several specimens of a group of swimming reptiles1 called plesiosaurs1 which swarmed the ,jurassic and ,cretaceous seas1 have been found with highly polished stones inside the rib basket4 ,also a mass of highly polished stones was found similarly associated with one dinosaur1 ,protiguanodon1 in the ,lower ,cretaceous rocks of ,mongolia4 ,on the other hand1 no highly polished stones have been found associated with the specimens in the ,dinosaur ,quarry or anywhere in the quarry4 ,a search of the many publications on dinosaurs has not turned up any mention of highly polished stones being associated with any of the many specimens found in ,north ,america4 ,thus the evidence which we have does not permit us to say that the dinosaurs found in the quarry did or did not possess gizzard stones4 ,the ,climate1 ,life1 and ,landscape of ,jurassic ,time ,the geologists who attempt to reconstruct the geography and climate of the ,jurassic ,period first gather all possible facts and try to fit them together to form a logical pattern4 ,the results are then examined for weak points and an attempt is made to find field evidence throwing light on these weak points4 ,the final result represents the sum of our knowledge at the time but is subject to change as new facts are obtained4 ,thus the following outline represents present thinking that may be changed somewhat by future studies4 ,the land for miles around the ,dinosaur ,quarry was a low-lying desert in early ,jurassic time4 ,the mountains you see now had not yet been formed1 and the whole desert area lay close to sea level4 ,great restless sand dunes drifted across this level land to form a blanket #gjj feet thick4 ,as the earth's crust sank1 these dunes were covered by a long arm of an arctic sea that extended southward along the present trend of the ,rocky ,mountains across ,canada1 ,montana1 ,wyoming1 and ,utah4 ,millions of years later1 in late ,jurassic time1 when the ,morrison formation was deposited1 the area rose again and the stage was set for the dinosaurs4 ,imagine if you can1 the vast plains extending from ,mexico to ,canada and from central ,utah to the ,mississippi ,river4 ,to the west were high mountains in the ,great ,basin region of ,nevada and western ,utah4 ,from these highlands flowed great sluggish streams that carried large amounts of sand and silt4 ,since the plains were almost flat1 swamps and small lakes were probably numerous4 ,the streams may have changed their courses from time to time as they were not confined to deep valleys4 ,when the whole region emerged from the sea the climate became more humid4 ,volcanoes were active far to the west2 the winds carried clouds of ejected dust eastward and deposited them on the plains4 ,semi-tropical conditions probably existed throughout the ,united ,states and in parts of ,canada4 ,these deposits are called the ,morrison formation4 ,the warm humid climate provided ideal conditions for plant growth4 ,great forests of lush vegetation covered the land4 ,many of these plants have since disappeared1 but some of their related species may be found today in the tropics4 ,most of the plants of our ,temperate ,zone had not yet evolved4 ,however1 there were tall stands of a type of pine1 and other evergreens4 ,there were also gingkos and curious tree ferns4 ,various herb ferns formed a ground cover as thick and lush as grass on a well-watered prairie4 ,palmlike ferns resembling today's cycads were common1 while along the river grew horsetail rushes like those living today4 ,flowering plants of the ,recent ,epoch of geologic time 7in which we are now living7 had not yet made their appearance4 ,thus the hardwood1 broadleaf forests of oak1 elm1 beech1 maple1 and similar trees were absent4 ,so too were the flowering shrubs familiar to the ,temperate ,zone4 ,even the grasses were missing4 ,however1 if you could picnic in this strange plant world you would soon be slapping mosquitos and cursing the ants4 ,for even in such ancient times these insects were present2 and so were a great variety of other insects as is known from the more than #a1jjj species that have been discovered in ,jurassic rocks4 ,among them were representatives of most modern orders such as grasshoppers1 beetles1 moths1 ants1 and flies4 ,jurassic insects probably looked much like those of today4 ,among the most interesting of the strange reptiles were the pterosaurs that dominated the skies4 ,they resembled the modern bats in some ways but their leathery wings were supported on each side by one finger instead of four1 and their skins were scaly or bare instead of hairy4 ,some forms had long tails that were flattened at the tip and helped them balance in flight1 but others were tailless4 ,some pterosaurs were no larger than sparrows while others had wing spans of #c to #d feet4 ,crocodiles sunned themselves on the banks of sluggish streams and lakes4 ,they probably looked a good deal like those that live in modern swamps and their habits were similar4 ,many a small dinosaur fell victim to their stealthy attack and disappeared beneath the waters of some ancient stream4 ,birds have been found in ,upper ,jurassic rocks of ,germany and may have lived here too4 ,their fossil remains would probably have been classed as reptiles had not feather imprints been a part of them4 ,about the size of crows1 these reptile-like birds had small conical teeth1 three-clawed fingers on each wing1 and a long tail instead of the fan of feathers seen on modern birds4 ,small mammals were also living at the time the ,morrison formation was being deposited and their remains have been found in the dinosaur quarry at ,como ,bluff1 ,wyo4 ,the largest ones were about the size of a house cat but the majority were much smaller1 probably about the size of today's mice4 ,we do not know much about the habits of these early mammals but they were probably rather shy and retiring4 ,this would be expected in the world of giants where they lived4 ,some of them lived in trees and there was one group whose skull characteristics resemble those of the rodents4 ,it is likely that these primitive mammals lived a life similar to that of the rodents millions of years later4 ,this1 then1 was the setting1 the stage upon which the dinosaurs played their leading roles4 ,although we have restricted our discussion to ,morrison time in northeastern ,utah1 the same or similar animals lived all over the world4 ,worldwide humid and mild climates produced a similarity of plant and animal life during most of the ,mesozoic ,era whose like has not been seen in the last #fj million years4 ,it was a strange world and ruled by strange animals1 but it must have been an interesting one4 ,,how ,,do ,,we ,,know8 ,this is a good time to stop and try to explain that this story1 of plants and animals of the past1 has a firm foundation in today's facts--it is not a fantasy4 ,the methods by which geologists and paleontologists have established the age1 climate1 and life of ,morrison time cannot be described for you here in detail4 ,to attempt such a description would require too much space and would probably seem dull to most readers4 ,perhaps the best approach is to describe some features and explain how they contribute to our knowledge4 ,the rocks that were deposited here in ,morrison time tell us much of the story4 ,the sandstones were once stream sandbars or perhaps beaches around lakes4 ,the shale1 siltstone1 and clay were muddy stream or lake bottoms4 ,the discontinuous ledges of conglomerate probably represent gravel bars formed during flood stages or at places where the stream currents were very swift4 ,just rocks you may say--but look closely4 ,a piece of sandstone contains grains of sand that differ from each other in size1 shape1 and composition4 ,frequently these characteristics point to the source of the sandstone and tell something about the conditions at the time it was deposited4 ,chunks of black material are examined closely and prove to be charcoal--carbonized remains of plants4 ,microscopic examination of clay fragments reveals shards of volcanic glass and ash that speak of active volcanoes4 ,sometimes these clays bear the carbonized imprints of delicate plants that long ago sank to the bottom of some lake or stream where they were buried and fossilized4 ,the fossils themselves are most important in reconstructing conditions of the past4 ,we find the shells of fresh-water clams in the sandstones with dinosaur bones4 ,crocodile bones are also common4 ,we are reasonably sure1 then1 that these deposits of sand and mud were formed in rivers and lakes when the climate was mild4 ,we reason by analogy4 ,for example1 fossil plants and animals have counterparts or descendants in the world of today4 ,we assume1 in the absence of contrary evidence1 that the fossil animals lived like their present-day counterparts4 ,although no birds1 mammals1 or pterosaurs have been found in this quarry1 they were probably living here with the dinosaurs4 ,it is possible1 in fact probable1 that some modern animals and plants live in different environments than did their ,morrison ancestors and relatives but we have no way of knowing which ones they were4 ,we can only take the data available1 arrange them as logically as possible1 and continue the search for more4 ,some may scoff at such methods of reasoning yet they do provide good results4 ,what other methods can be used when the world under investigation lies millions of years in the past8 ,animals from the ,quarry ,in the rocks of the ,morrison formation at the quarry1 both orders of dinosaurs are found--,saurischia and ,ornithischia4 ,paleontologists have divided the dinosaurs into these two groups on the basis of important skeletal differences4 ,these differences remain constant for the orders and vary within each order only in small details4 ,the important structural difference in dinosaurs is found in the pelvis4 ,in all land vertebrates1 the pelvis is made up of three pairs of bones called the ilium1 pubis1 and ischium4 ,the paired ilium is joined to each side of the backbone and projects downward to meet the pubis and ischium at the socket for the head of the thigh bone4 ,the pubis forms the front third and the ischium the rear third of this socket4 ,in the order ,saurischia the bones of the pelvis are arranged as in most reptiles and mammals4 ,in the order ,ornithischia the pubis extends backward along the ischium as it does in the birds4 ,two types of saurischian dinosaurs are found in the quarry4 ,antrodemus1 a flesh-eating type1 was about the size of a horse1 but was two-footed4 ,it had strong sharp claws on its feet4 ,its teeth were about #b inches long1 flattened from side to side and with fine serrations on front and back edges4 ,actually it is not known whether ,antrodemus overpowered and killed the large swamp-living dinosaurs1 or merely fed on their carcasses after they had died from other causes4 ,however1 there has been found in the quarries at ,como1 ,wyo41 a partial skeleton of ,apatosaurus with grooves on the bones which suggest tooth marks4 ,the spacing of these grooves fit the spacing of the teeth of a specimen of ,antrodemus found in the same quarry4 ,illustration3 ,a4 ,,ornithischian ,,pelvis4 ,b4 ,,saurischian ,,pelvis4 ,,key3 ,,il--,,illium2 ,,is--,,ischium2 ,p--,,pubis4 ,the plant-eating dinosaurs of the order ,saurischia which are found in the quarry were all four-footed4 ,they had bodies about the size of an elephant or larger4 ,the principal differences between the flesh- and plant-eating dinosaurs were the length of the neck and tail1 the details of their skull structure1 and other parts of their skeleton4 ,apatosaurus is perhaps the most familiar dinosaur to most of us4 ,its hind legs were much longer than its front ones and gave the animal a high-hipped1 stooped appearance4 ,apatosaurus was about #gj feet long and probably weighed close to #dj tons4 ,diplodocus was longer 7one of them #ge feet7 but was slender and lightly built4 ,its neck was longer and it had a whiplash tail that looked much like the tail of the modern whiptailed lizard4 ,diplodocus also had long pencil-like teeth different from those of any other known dinosaur4 ,barosaurus has an extremely long neck with long individual neck bones4 ,two members of the genus ,camarasaurus are similar to each other except for size2 one was small1 but the other was as large as ,apatosaurus4 ,camarasaurus had longer front legs than ,apatosaurus and was generally better proportioned4 ,illustration3 ,antrodemus1 ,,the ,,ferocious ,,carnivore ,,of ,,morrison ,,time4 7,,from ,a ,,drawing ,,by ,,charles ,r4 ,,knight4 ,,courtesy1 ,,american ,,museum ,,of ,,natural ,,history47 ,illustration3 ,,the ,,great ,,saurischian ,,plant-,,eater ,apatosaurus louisae--,,about #gj ,,feet ,,long4 7,,from ,a ,,drawing ,,by ,a4 ,,avinoff1 ,,carnegie ,,museum47 ,fossils of the saurischian plant-eaters are found much more frequently than those of flesh-eaters and are usually in sedimentary rocks which contain beds of clam shells4 ,for this reason it seems probable that they waded lagoons and streams1 feeding on aquatic and bank-side vegetation4 ,the suggestion has been made that the larger dinosaurs could not even walk on dry land because their weight would have crushed the bones of their feet2 they needed the buoyancy of water to help support them4 ,however1 footprints of a huge dinosaur1 much larger than any from the quarry1 have been found near ,glenrose1 ,tex4 ,the large footprints were made on a sandy beach of a sea in ,lower ,cretaceous time4 ,thus we know that they could walk on dry land if they wanted to4 ,all of the dinosaurs of the order ,ornithischia were plant-eaters1 and were of both two- and four-footed types4 ,the two-footed types found in the quarry are ,camptosaurus1 ,dryosaurus1 and ,laosaurus4 ,these forms had well developed front legs1 though much shorter than their hind legs1 which suggests that they may have dropped down on 8all fours0 while feeding or resting4 ,the teeth were small1 chisel-shaped1 and fitted only for cropping vegetation4 ,the larger specimens of ,camptosaurus reached a length of #ag feet but ,laosaurus was only #b feet long4 ,stegosaurus is the only quadruped 7four-footed7 of this order found in the quarry4 ,it had long hind legs and very short front legs4 ,it reached a length of #ah to #bj feet and was #aj to #aa feet high over the hips4 ,the most characteristic feature of this form was the double row of bony plates down the back and the group of spikes at the end of the tail4 ,the teeth were similar to those of ,camptosaurus1 but much more numerous4 ,only two other groups of reptiles have been found in the quarry at ,dinosaur ,national ,monument and their remains are rare4 ,these are the crocodiles and turtles4 ,two crocodiles are known2 the larger one1 ,goniopholis1 was about the size of existing alligators and did not differ in external appearance from present-day crocodiles4 ,the smaller one was less than a foot long and resembled a #b weeks' old alligator as much as anything4 ,however1 we know from the texture of the surface of the bone that it was not a young animal4 ,the turtle1 ,glyptops1 was about the same size and general appearance as the pond turtles of today4 ,,why ,,so ,,many8 ,the partial skeletons of more than #bj individual dinosaurs and the scattered bones of about #cjj more have been discovered in the ,dinosaur ,quarry4 ,many of the best specimens may be seen today at museums of natural history in the larger cities of the ,united ,states and ,canada4 ,the quarry is easily the largest and best preserved deposit of ,jurassic dinosaurs known today4 ,how and why did so many dinosaur skeletons accumulate here8 ,how were they preserved8 ,these are among the common questions asked of park rangers and naturalists at ,dinosaur4 ,the answer is a combination of circumstances and luck4 ,many people get the impression from the mass of bones in the quarry wall that some catastrophe such as a volcanic explosion or a sudden flood killed a whole herd of dinosaurs in this area4 ,true enough this could have happened1 but it probably did not4 ,the main reasons for thinking otherwise are the scattered bones and the thickness of the deposit4 ,in other deposits where the animals were thought to have died together1 the skeletons were usually complete and often all the bones were in their proper positions1 or articulated4 ,in a mass killing the bones would have been deposited on the stream or lake bottom together at the same level1 but in this deposit the bones occur throughout a zone of sandstone about #ab feet thick4 ,the mixture of swamp dwellers and dry-land types also seems to indicate that the deposit is a mixture derived from different sources4 ,rounded fragments of fossil bone have been discovered in the quarry--fragments that attained their pebblelike shape by rolling along the stream bottom4 ,if the mass of bones was not the result of catastrophe what did happen8 ,the quarry area is a dinosaur graveyard1 not a place where they died4 ,a majority of the remains probably floated down an eastward flowing river until they were stranded on a shallow sandbar4 ,some of them1 such as the stegosaurs1 may have come from far-away dryland areas to the west4 ,perhaps they drowned trying to ford a tributary stream or were washed away during floods4 ,some of the swamp dwellers may have mired down on the very sandbar that became their grave while others may have floated for miles before being stranded4 ,even today similar events take place4 ,when floods come in the spring1 sheep1 cattle1 and deer are often trapped by rising waters and frequently drown4 ,their bloated carcasses float downstream until the flood recedes and leaves them stranded on a bar or shore where they lie1 frequently half buried in the sand1 until they decompose4 ,early travelers on the ,missouri ,river reported that shores and bars were frequently lined with the decomposing bodies of bison that had perished during spring floods4 ,in ,dinosaur ,national ,monument1 the positions in which partial skeletons of the dinosaurs lie suggest that they decomposed on a sandbar4 ,the bones on the underside of a skeleton are often arranged as they were when the animal was alive1 while those on the upper or exposed side may be scattered4 ,such scattering would be expected as the ligaments and muscles holding the bones together decomposed2 stream currents and scavengers could then disperse them4 ,stream currents are suggested by the position of the long1 flexible tails and necks of the large plant feeders4 ,these1 like streaming water plants in a river1 trail downstream to the east4 ,illustration3 ,camptosaurus--,,an ,,arnithischian ,,plant-,,eater4 7,,drawn ,,by ,j4 ,g4 ,,german4 ,,courtesy1 ,,american ,,museum ,,of ,,natural ,,history47 ,,how ,,were ,,they ,,preserved8 ,the concentration and burial of dinosaur bones is only the beginning of the fossil story4 ,the combination of circumstances which operated here was a common one and yet fossil quarries are rare4 ,why8 ,the bones have to be preserved and this seldom happens4 ,the bones that are buried in one flood are frequently unearthed and scattered by the next4 ,those that are exposed to the weather usually disintegrate completely in a few years4 ,the bones in the ,dinosaur ,quarry did not4 ,sometime after they were buried1 the organic minerals of the bones were more or less completely replaced by minerals of inorganic origin such as silica4 ,no one knows exactly why or how this happened1 but it did4 ,most geologists think this replacement process occurs when subsurface or ground water containing soluble and colloidal minerals dissolves a molecule of the bone and immediately replaces it with a new mineral4 ,roughly such a process is like removing red bricks from a house and substituting yellow4 ,when the substitution is complete1 the house still has the same dimensions but it is composed of different materials4 ,the replacement was a faithful one1 too1 because microscopic structure of the original bone was faithfully reproduced by the replacing minerals4 ,illustration3 ,,road ,,map ,,dinosaur ,,national ,,monument ,,utah - ,,colorado ,high-resolution ,map ,following ,morrison time1 thousands of feet of younger sediments were deposited on the sandbar that contained the dinosaur bones4 ,the whole sequence of sediments was compacted into rock and some bones were crushed and distorted4 ,,how ,,were ,,they ,,exposed8 ,after the sediments became rock and the bones had probably been replaced by stone 7fossilized71 this part of the world1 which lay near or below sea level for millions of years1 began to rise4 ,great forces acted upon the earth's crust4 ,these forces created faults1 or fractures1 in the rock crust along which movement occurred4 ,and what had once been sea bottom was moved upward and became lofty mountains4 ,this titanic change has been called the ,laramide ,revolution2 it closed the ,mesozoic ,era with the formation of the ,rocky ,mountains4 ,illustration3 ,stegosaurus4 ,,an ,,armored ,,dinosaur ,,of ,,the ,,jurassic ,,period4 7,,from ,a ,,drawing ,,by ,,charles ,r4 ,,knight4 ,,courtesy1 ,,american ,,museum ,,of ,,natural ,,history47 ,although the effects of the ,laramide ,revolution were not as profound at ,dinosaur as they were east of it1 they were quite important4 ,the rocks were lifted to form the southwest flank of ,split ,mountain--a small arch1 or anticline1 on the south side of the ,uinta ,mountains4 ,this mountain building explains the pronounced southward tilt of the ,dinosaur ,ledge and other rock layers visible in the quarry area4 ,as the land rose1 streams flowed more rapidly1 cutting deeper into the rocks and carrying away the debris4 ,gradually thousands of feet of this debris--shale1 sandstone1 and clay--were stripped away through erosion4 ,finally all the material on top of the ,morrison sandbar weathered away4 ,some #adj million years after burial the fossil bones were exposed by the agent that had buried them so long ago--running water6 ,all that remained was for them to be found1 and that was the luckiest chance of all4 ,just suppose they had been uncovered a million years ago--only a second in geologic time4 ,no one would have been present to discover them1 and through the years they could well have crumbled into dust and been blown away4 ,why ,did ,dinosaurs ,become ,extinct8 ,at ,dinosaur ,national ,monument only ,morrison rocks of the upper ,jurassic ,period contain the fossil bones of dinosaurs4 ,after ,morrison time1 the ,cretaceous seas invaded this area4 ,more than #e1jjj feet of sandstone1 shale1 and mudstone were formed from sediments deposited in these seas4 ,elsewhere in ,north ,america and the rest of the world1 the diversity and numbers of dinosaurs actually increased4 ,entirely new groups evolved and achieved success in the battle for survival4 ,the climax of reptile development seems to have come near the end of ,cretaceous time in the ,mesozoic ,era4 ,as the dinosaurs ruled the continents1 so did other strange reptiles dominate the seas4 ,had you been able to see this ancient world1 you would surely have been convinced that the dinosaurs and other reptiles would rule forever4 ,but it was not to be4 ,the dinosaur hordes were wiped out and the reptiles reduced to the position of relative insignificance they occupy today4 ,such a profound and sudden change in the evolutionary trend of life must have had a cause1 and scientists have sought it4 ,several theories have been proposed to explain extinction of dinosaurs1 and they are most interesting4 ,at the end of ,cretaceous time1 some of our great mountain ranges were formed4 ,it was a time of earthquakes and of volcanoes that belched forth clouds of ash and rivers of molten rock4 ,some people would say these catastrophic events killed all the dinosaurs4 ,the scientist shakes his head4 ,if these events killed dinosaurs1 why not the other animals that lived with the dinosaurs4 ,and what of those parts of the world that had no volcanoes1 what killed dinosaurs there8 ,changes in environments1 the drainage of lakes and swamps as young mountains rose1 changes in vegetation as new plants replaced old1 and sudden shifts of climate occurred4 ,these conditions could explain local extinction1 but there were places where these changes did not occur and yet all dinosaurs in all places died4 ,a one-time favorite theory suggested that increasing numbers of small mammals ate dinosaur eggs1 but there were many mammals eating dinosaur eggs during all of ,cretaceous time and the dinosaur hordes increased4 ,many more mammals during succeeding ages have not killed off the turtles1 snakes1 lizards1 and crocodiles that lay eggs and exist in great numbers today4 ,some disease or combination of plagues may have swept the dinosaurs into extinction4 ,if so1 no evidence has been found to date that confirms or denies4 ,however1 most paleontologists do not accept this theory4 ,these are some of the theories that have been advanced to explain the sudden extinction of dinosaurs throughout the world4 ,each theory will explain the death of some dinosaurs in some places but attempts to apply any of them1 or combinations of them1 to worldwide extinction have failed4 ,this dinosaur story is like a mystery thriller with the last pages torn out4 ,a most important part is missing4 ,that is true and the paleontologist knows it4 ,he also knows the riddle will probably never be solved4 ,he might point out1 however1 that no one has successfully explained the extinction of the passenger pigeon which occurred quite recently1 nor do we know why some other species of wildlife are on the brink of extinction today4 ,the paleontologist is not the only one who must say1 8,i don't know40 ,history and ,development of the ,quarry ,,discovery ,,and ,,early ,,years ,no one knows how long the old bones had been weathering out of the hills of what is now ,dinosaur ,national ,monument before the first man saw them4 ,curious ,indians1 wandering between the upturned ridges of ,mesozoic rocks1 picked up fragments and carried them off to their camps where they are now found among the arrow points1 ax heads1 and corn-grinding stones4 ,in #aggf1 the ,spaniard1 ,father ,escalante1 passed within sight of today's dinosaur quarry1 not dreaming of the antiquity hidden there4 ,maj4 ,john ,wesley ,powell1 on his second voyage down the ,green ,river in #ahga1 recorded the presence of 8reptilian remains0 in the area1 but wrote nothing more about them4 ,sheepherders1 cattlemen1 and hunters observed them and were impressed in proportion to their understanding4 ,but1 through all the years1 the nature of the bones remained a mystery4 ,illustration3 ,,earl ,,douglass1 ,,discoverer ,,of ,,the ,,dinosaur ,,quarry4 ,then1 in #ahic1 this mystery was solved4 ,o4 ,a4 ,peterson1 a scientist from the ,american ,museum of ,natural ,history1 while conducting field work in the ,uinta ,basin to the south of the present monument boundaries1 discovered bones out-cropping from a recognized fossil-bearing stratum4 ,the stratum was the #adj1jjj1jjj year-old ,morrison formation4 ,the bones8 ,peterson reported them as the remains of dinosaurs4 ,that report was to have an important influence1 #ae years later1 in directing a fellow paleontologist from the ,carnegie ,museum in ,pittsburgh to investigate the area4 ,earl ,douglass was the paleontologist's name4 ,in #aijh1 he and ,w4 ,j4 ,holland1 ,director of the ,carnegie ,museum1 found themselves in the region of ,peterson's discovery1 searching for dinosaur remains4 ,they extended their search to the north and thence along the ,morrison hogback that flanks ,split ,mountain4 ,bone was found--not much1 but enough to bring ,douglass back the following summer and in company with ,george ,goodrich1 a local resident1 to pursue the hunt4 ,the hunt came to a triumphant climax on ,august #ag1 #aiji1 when--to quote from ,douglass's diary--8,at last in the top of the ledge where the softer overlying beds form a divide 444 ,i saw eight of the tail bones of a ,brontosaurus ,apatosaurus in exact position40 ,,starting ,,the ,,quarry ,this was the beginning--the beginning of the celebrated dinosaur quarry which was to yield such a multitude and variety of ancient forms to science1 and eventually lead to the establishment of ,dinosaur ,national ,monument4 ,douglass proceeded to dig into the solid rock along those original eight tail bones and found other parts of the skeleton4 ,in time1 the almost complete frame of the ,apatosaurus was exposed4 ,the skull was missing and parts of the limb bones1 but this was to be expected1 as fossil vertebrates are rarely preserved in their entirety4 ,what was not expected were the remains of a smaller dinosaur comingled with those of its huge contemporary4 ,,extent ,,and ,,development ,,of ,,the ,,find ,douglass was elated4 ,this was more than a 8one strike06 ,how much more1 only further digging would tell4 ,sensing a large-scale operation1 he informed the ,carnegie ,museum of his prospects and readied things with the intensity of a man at the gate of destiny4 ,from the neighboring ranches he recruited men1 horses1 and equipment4 ,he sent for his wife and child4 ,he constructed a road to the discovery site1 built a five-room cabin out of logs and lumber1 converted a sheepherder's camp wagon into an office1 selected ground for future planting1 bought a cow4 ,a forge was set up4 ,tools were purchased4 ,back at the museum1 ,andrew ,carnegie1 himself1 evinced interest4 ,he had always wanted something 8as big as a barn0 for his institution4 ,a special annual field fund of #e1jjj was added to the regular budget to carry on the work4 ,within a year1 ,douglass and his men had run a cut over a hundred feet long in the hard sandstone1 digging down along the almost perpendicular slant of the rock4 ,at the base of this1 rails were laid and small mine carts introduced to haul away the cuttings from the rapidly developing quarry4 ,new specimens appeared3 ,a small plant-eating dinosaur known as ,dryosaurus2 an armored form called ,stegosaurus2 and another large creature like the ,apatosaurus4 ,best of all1 the ,apatosaurus ,no4 #a was well on its way out of the rock and would soon be ready to ship to the ,carnegie ,museum in ,pittsburgh4 ,illustration3 8444 ,i ,,saw ,,eight ,,of ,,the ,,tail ,,bones ,,of ,a ,brontosaurus ,,in ,,exact ,,position40 7,,from ,,douglass' ,,diary1 #aiji4 ,,shown ,,in ,,photo ,,is ,,douglass' ,,assistant1 ,,elder ,,goodrich47 ,illustration3 ,,the ,,first ,,cut ,,in ,,the ,,quarry1 ,,as ,,it ,,looked ,,in #aiaj4 7,,courtesy1 ,a4 ,s4 ,,coggeshall47 ,illustration3 ,,sample ,,view ,,of ,,dinosaur ,,remains ,,as ,,they ,,were ,,uncovered ,,in ,,the ,,quarry4 ,,thigh ,,bone ,,near ,,man4 7,,courtesy1 ,a4 ,s4 ,,coggeshall47 ,illustration3 ,,quarry ,,operations4 ,,saurischian ,,plastered ,,pelvis ,,upper ,,center4 7,,courtesy1 ,a4 ,s4 ,,coggeshall47 ,in #aiac1 after #c years of laboratory work in the ,carnegie ,museum the big ,apatosaurus was on its feet in the ,hall of ,vertebrate ,paleontology--#a of the #d mounted specimens of this genus in the country and the most perfect of all4 ,prepared and erected by ,arthur ,s4 ,coggeshall and his associates1 it measures #ga feet long and stands #ae feet tall at the arch of the back4 ,as the excavating progressed it was not long before the diggings became what is known to the profession as a 8general quarry40 ,dinosaurs of 8all kinds and sizes0 were showing up4 ,other quarries of this type had been developed in previous years in the ,morrison formation at ,como ,bluff1 ,wyo41 and ,canon ,city1 ,colo41 but they contained nothing like the variety of forms found here4 ,moreover1 these at the monument were better preserved and the skeletons more intact4 ,the remains most frequently encountered in the diggings were those of sauropods--the huge plant-feeding dinosaurs with long tapering extremities that lumbered about on four pillar-like legs4 ,camarasaurus and the larger ,apatosaurus were typical members of this group1 and their numerous bones show them as being common animals of their time4 ,more common were the ,diplodoci1 of the exaggerated neck and even longer whiplash tail4 ,this genus distinguished itself by producing not only the largest amount of skeletal material from the quarry1 but also the largest number of skulls--those rarest of fossils4 ,one skull was found in exact position with the neck bones1 which settled all doubts as to the details of this animal's head piece4 ,the longest ,diplodocus to come from the monument extended #ge feet4 ,contrast this with the diminutive ,laosaurus1 a #b-;foot biped which ranks as the smallest dinosaur yet taken from the deposit4 ,this tiny creature had hollow limb bones and was one of the agile1 quick-running types4 ,only one was found4 ,when discovered1 ,douglass thought it a 8baby0 dinosaur1 but study proved it to be a full-grown specimen4 ,the condition of the skeleton reflected considerable agitation before and after burial4 ,it lay on its back1 the limbs distended4 ,the tail was gone and the skull crushed4 ,in many respects1 the most interesting dinosaur found was the sauropod1 ,barosaurus4 ,it was an extremely long-necked form1 some of the individual cervical vertebrae measuring #c feet in length4 ,two specimens were excavated4 ,the flesh-eaters1 as might be expected from their scarcity in other localities1 made but a small showing4 ,two specimens of ,antrodemus were unearthed4 ,thirty feet long1 this animal was the ranking predator of its day1 although hardly comparable to the towering ,tyrannosaurus that entered upon the earthly scene at a later age4 ,stegosaurus remains--so abundant that ,douglass grew tired of them--added a bizarre note4 ,an armored form1 it was equipped with a frill of bony plates that extended the length of the back and terminated in a pair of sharp spines4 ,its chief claim to fame rests in its supposed two sets of 8brains10 one a motor-control center situated in the hip region1 and the other in the usual place4 ,everywhere they dug1 the excavators found fresh material--a vast jumble of bones so concentrated and intermingled as to make it difficult to distinguish one specimen from another4 ,douglass was amazed4 ,obviously1 it was not with animals of a single area that he was dealing1 but of an entire region4 ,he was dealing with a dinosaur fauna4 ,he was also perplexed4 ,how did so many different types happen to occur in one small locality8 ,slowly1 as ,douglass's acquaintance with the deposit grew1 the answer came4 ,it was1 he reasoned1 the work of a river4 ,the sandstones were ancient sediments4 ,in their structure and composition lay the story of swift swirling currents4 ,the coarse granular texture told of fast water2 the crossbedding1 of shifting channels2 the grouping of the bones into clusters1 of eddies4 ,it all added up to an old delta deposit at the mouth of a river1 a region of bars where the carcasses of dinosaurs brought down stream accumulated4 ,settling1 the great hulks became buried as they sank into the receptive sand4 ,a number of carcasses multiplied 444 and slowly1 as flesh and ligament decayed1 the bones became mingled1 eventually to petrify and remain preserved through the ages4 ,,work ,,methods ,at the quarry1 excavating continued summer and winter4 ,the methods employed were those that paleontologists had used for decades4 ,there was no compressed air1 no labor-saving devices4 ,the work was done by hand4 ,the crew1 which seldom exceeded four men at any one time1 became veterans in the art of fossil extraction4 ,the bone was brittle2 the encasing sandstone1 hard4 ,it required toil1 patient direction1 and a knowledge of anatomy4 ,judiciously placed charges of giant powder shattered the overburden4 ,hand drills1 wedge-and-feather1 and crowbar worked the rock away1 until the bone layer was encountered4 ,the slow attrition by hammer and chisel accomplished the final delicate separation of the remains from the enclosing matrix4 ,team-and-scraper and small handcarts removed the rubble that swiftly accumulated in the cut4 ,as the bones were chiseled from the quarry face in large blocks of rock1 they were encased in strips of burlap dipped in flour paste4 7,later1 plaster of ,paris supplanted the flour paste47 ,then they were lowered by rope onto a mule-drawn skid and 8snaked0 down the trail into the gulch to await boxing4 ,illustration3 ,,removing ,a ,,large ,,thigh ,,bone ,,from ,,the ,,quarry ,,wall ,,during ,,the ,,carnegie ,,museum ,,operations4 7,,courtesy1 ,a4 ,s4 ,,coggeshall47 ,illustration3 ,,plastered ,,specimen ,,removed ,,from ,,the ,,quarry ,,during ,,the ,,carnegie ,,museum ,,operations4 7,,courtesy1 ,a4 ,s4 ,,coggeshall47 ,transporting the fossils from quarry to railhead was a major undertaking4 ,it required wagon trains--#d-;horse teams hauling high-wheeled freight wagons over #fj miles of rutted roads to ,dragon1 ,utah4 ,there the precious goods were loaded onto boxcars of the now abandoned narrow gauge ,uintah ,railway1 later to be transhipped to the standard gauge ,denver ,rio ,grande line at ,mack1 ,colo4 ,,further ,,development ,specimens continued to show in record abundance1 most of them duplicating the earlier finds of ,diplodocus and ,stegosaurus4 ,but there were new forms1 too4 ,one of them was a ,camptosaurus1 the first to be found at the quarry4 ,it was a modified biped of plant-eating habits1 a little more than #aj feet long1 with its skull and part of the tail missing4 ,by #aiba the deposit had been worked to a length of #djj feet east and west1 and to a depth of about #fj feet4 ,rock was being stripped from the quarry face at the rate of approximately #bj1jjj cubic feet annually1 and the chisels of ,douglass and his men had penetrated to the richest bone-bearing zone4 ,in the following year they uncovered one of the most perfect skeletons of a dinosaur ever exhumed4 ,it was a small sauropod named1 ,camarasaurus lentus4 ,when found1 its #ag-;foot vertebral column was practically intact1 except for a few tail segments4 ,the skull was in place1 and the limbs in their approximate positions4 ,it was an important find scientifically4 ,the position of the limbs gave clear evidence of the manner in which these animals carried themselves4 ,the articulation between the thigh bone and the pelvis showed conclusively that sauropods walked with their legs more-or-less vertical to the body and not with the bowed-out crawling posture habitual to lizards1 as many scientists had supposed4 ,the skull was the finest known for this genus4 ,it was complete even to the sclerotic ring--a complex of bony plates which surrounded the living eye and protected it4 ,as exhibit material it was without rival4 ,it was mounted as found1 lying on its side1 the bones fixed in death in the matrix in which they had been preserved--a fitting climax to the #ac consecutive years that had seen an unknown sandstone ridge in ,utah become ,dinosaur ,national ,monument4 ,in those #ac years the ,carnegie ,museum had taken from the quarry parts of #cjj dinosaur specimens1 #b dozen of which were mountable skeletons4 ,ten different species were represented4 ,it was the best collection of ,middle ,mesozoic monsters in the world4 ,in the years that immediately followed1 the still-rich 8dig0 was worked by two other organizations--the ,smithsonian ,institution and the ,university of ,utah4 ,illustration3 ,camarasaurus ,,skeleton--,,the ,,most ,,perfect ,,removed ,,from ,,the ,,quarry4 7,,courtesy1 ,,carnegie ,,museum47 ,but finally the museums had reaped their harvest4 ,the fruits of the harvest had gone to enrich many of their finest displays4 ,however1 still buried in the untouched part of the wall were the remains of still more dinosaurs4 ,all that was needed was to reveal them4 ,the #fg tilt of the rock made it a perfect exhibit face4 ,strip off the overlying layers1 expose the skeletons1 and relief them in place4 ,this had been ,douglass's idea as far back as #aiae1 when he recorded it in his diary4 ,,protecting ,,the ,,quarry ,but ,douglass was not the only one to realize the necessity of preserving this unique fossil record of the dinosaurs for people of today and the future to see on the spot4 ,officials of the ,carnegie ,museum realized the extraordinary nature of the deposits and their contribution to our knowledge of the past2 and they were not long in taking steps to protect the dinosaur quarry4 ,to preserve it for science1 they sought to lay claim to it as a mineral property4 ,but their claim was disallowed by the ,u4 ,s4 ,department of the ,interior1 because fossil bones could not be classed as a mineral within the meaning of the mining laws4 ,the museum pressed its case1 this time with results--but not what they expected4 ,the outcome was not the establishment of a mere mineral claim1 but of a national monument4 ,under the provisions of the ,antiquities ,act1 to safeguard and preserve objects and areas of significant scientific or historic interest1 the dinosaur quarry and #hj acres of surrounding land were declared a national monument on ,october #d1 #aiae4 ,less than a year later it was included in the newly created ,national ,park ,system4 ,several things contributed notably to this action to protect the quarry4 ,they were3 the exceptional preservation of the bones2 the number1 variety and completeness of the skeletons2 the relative abundance of skulls1 consisting of #h or more in a complete state1 and about an equal number of incomplete ones2 and the finding of the first complete tails4 ,in #aibc1 knowing that the quarry was protected1 and that the scientific collection of the fossil bones for museum exhibit was at an end1 ,earl ,douglass turned again to the idea of making a perfected exhibit of the fossils right where they lie4 ,his letter to ,dr4 ,walcott1 secretary of the ,smithsonian ,institution1 reads1 in part1 8,i hope that the ,government1 for the benefit of science and the people1 will uncover a large area1 leave the bones and skeletons in relief and house them in4 ,it would make one of the most astounding and instructive sights imaginable40 ,illustration3 ,,architect',s ,,drawing ,,of ,,visitor ,,center ,,at ,,quarry ,,site4 ,this is precisely what the ,government had in mind and1 through the agency of the ,national ,park ,service1 intended to accomplish4 ,plans for an in-place exhibit were drawn up4 ,but many years were to elapse before the plans passed from blueprint into reality4 ,in the meantime1 the quarry entered the second phase of its existence1 a dormant period from a scientific viewpoint1 but one in which the forces of the future gathered ground4 ,during the #aicj's the monument served as a transient camp4 ,a4 ,c4 ,boyle was installed as resident geologist and custodian for the ,park ,service4 ,under his guidance a program for the general development of the area was carried on1 financed largely by ,,wpa funds4 ,this entailed1 among other things1 the deepening and widening of the quarry cut1 and the construction of buildings later to accommodate the monument staff and exhibits4 ,the ,american ,museum of ,natural ,history became interested in the development at this time and1 through its curator of fossil reptiles1 ,barnum ,brown1 sought to initiate a joint effort with the ,park ,service for exhibiting the quarry remains4 ,,present ,,development ,it was not until ,september #aiec that the years of ,park ,service planning bore fruit1 and the work of developing an in-place exhibit for the monument was begun4 ,many factors operated to spring the project into being1 not the least of which was the active interest and wholehearted support of ,horace ,m4 ,albright1 a former ,director of the ,service4 ,theodore ,e4 ,white1 formerly with the ,smithsonian ,institution and with ,harvard ,university1 was placed in immediate charge1 under the supervision of ,jess ,h4 ,lombard1 the superintendent of the ,national ,monument4 ,his task1 and that of his associates1 was to expose the remaining specimens in the quarry wall and work them out in bas-relief4 ,a shelter had been built over the working space and power tools were introduced for the first time4 ,using compressed air1 the rock was scaled off with jackhammers and 8paving-breakers10 until most of the overburden had been removed4 ,subsequent probing into the bone layer was done with smaller chipping hammers1 mallet1 and chisel4 ,this operation continued through #aied and #aiee as1 slowly and carefully1 the extent of the skeletal material was determined4 ,it comprised parts of several large dinosaurs1 sufficient in quantity to justify the next step--the construction of a building to enclose the quarry face4 ,erection of this unusual structure1 the first of its design to be attempted1 commenced in #aieg and it was opened to the public in the following year4 ,now1 as one of the many development projects in its ,,mission #ff program1 the ,national ,park ,service has resumed the delicate work of uncovering this corner of the ancient world and preserving it in-place for all time4 ,the ,scene ,today ,if you stand at the overlook1 you will see the ,green ,river1 ,split ,mountain1 and a rolling plain to the south that stretches to a hazy line of mountains4 ,to many1 it is an unfamiliar land that lies strangely subdued beneath a blazing sun and an intensely blue sky4 ,that blue sky is the key to the kinds of plants and animals that live in this part of the monument4 ,they live most of their lives under blue sky1 and1 even when clouds do form over the mountains and drift across the lowlands1 the results are disappointing4 ,a high wind1 dust and sand1 a few drops of rain1 and the storm is over4 ,the climatic conditions under which local plants and animals live are conditions of extremes4 ,on summer days the temperatures may rise above #ajj1 although the nights are usually cool4 ,during the winter1 temperatures may skid to #cj below zero or more4 ,it is not uncommon for the thermometer to remain below zero for weeks on end4 ,but the most influential climatic factor is water--and there is little of it4 ,the total yearly precipitation is a little less than #h inches6 ,it is interesting then to find such a wide variety of plants and animals that not only survive but flourish under such rigorous conditions4 ,the methods used by plants in adapting to arid conditions are interesting and varied4 ,the wide-spreading1 shallow root system and thick stem of the cactus enhance collection and storage of water4 ,these strange plants are quite plump with stored water in the spring when the snows melt1 but they gradually lose this plumpness during the dry summer1 and by autumn many seem lifeless4 ,other plants conserve their water by minimizing the loss through their leaves4 ,this may be done in a number of ways4 ,the leaves of the spiny greasewood are covered with a waxy substance that inhibits water loss while the leaves of the sagebrush are covered with hairs or fuzz that serve the same function4 ,the leaves of the juniper are scale-like and really don't look like leaves at all4 ,the most direct method of preventing water loss through leaves is to drop the leaves themselves1 and this method is used to a greater or lesser degree by many desert plants4 ,the serviceberry is a good example of this method4 ,in late summer it looks dead1 and yet the following spring finds it robed in green and covered with flowers4 ,in contrast to the frugal habits of the plants just described1 the cottonwoods seem lavish indeed4 ,usually big trees1 they spread a canopy of green in whose shade rest birds and animals alike4 ,have you ever rested under a cottonwood8 ,if so1 you will remember it as being cool even on the hottest days4 ,part of the coolness was due to the hundreds of gallons of water which are transpired through the leaves each day4 ,because cottonwoods require so much water1 they usually grow along streams or near springs4 ,frequently they are seen along dry ravines where their thirsty roots tap the subsurface drainage that lies hidden below4 ,like the other plants however1 when the supply of water becomes inadequate they shed their leaves and wait for the next spring4 ,fast growing1 usually of large size1 and wasteful of water where water is dear1 the cottonwood seldom lives two hundred years while the twisted juniper on the dry1 rocky ledge frequently lives as much as five hundred4 ,illustration3 ,,split ,,mountain ,,gorge4 ,inconspicuous through most of the year are the flowering plants4 ,some of these are annuals--plants that grow from seeds1 mature1 bloom1 produce seeds1 and die in the span of a few short weeks4 ,when the snows melt and the sun warms the earth1 the seeds that survived the winter germinate4 ,the usually barren hillsides produce spots of green that soon spread to form patches as more and more plants mature4 ,lupine and locoweed are purple and heliotrope splashes color along the roads1 while the fragrant1 white1 evening-primrose dots the sandy hillside4 ,scarlet gilia and ,indian paintbrush add a touch of red to the scene1 and orange is provided by the mallow4 ,april1 ,may1 and early ,june provide the best flower show as spring rains supplement the moisture from melted snow4 ,their races won1 their seeds produced1 the annuals wither and fade away as the temperatures rise4 ,by the first of ,july little remains of the splendid show4 ,two plants do brighten the desert scene in ,august and ,september4 ,most common is the rabbitbrush1 a plant that grows almost everywhere4 ,it is rather inconspicuous except in late summer when its brilliant yellow blossoms turn the whole shrub golden4 ,the other is the bee plant of which there are two species3 one has yellow blossoms1 and the other has purple4 ,these tall plants grow along washes1 stream courses1 roads1 and irrigation ditches4 ,their delicate blossoms are always surrounded by insects drawn by the nectar the flowers produce in great quantities4 ,these1 then1 are a few of the typical plants4 ,each has adjusted its needs to those limiting factors--winter cold1 summer heat1 and aridity4 ,a great number of plants grow on the monument that have not been mentioned here1 but they are like the typical plants and have similar ways of meeting the problems of survival4 ,many people who profess an interest in nature admit they cannot get very excited about plants4 ,such disinterest may result in minimizing the importance of plants in the general scheme of nature4 ,that would be a major error4 ,the plants of the world are the foundation upon which other forms of life are dependent4 ,they alone are able to utilize the minerals in the soil and convert carbon dioxide and water to carbohydrates4 ,because of these abilities1 the parade of life has been able to advance only when the plants advance4 ,in the present as in the past1 the kinds and abundance of plants set definite limits as to the species and numbers of animals an area may support4 ,thus1 if man changes the plants of an area he will surely change the animals too1 whether he realizes it or not4 ,if you drive to the quarry in the heat of the day you will see only a few of the birds that live here4 ,they don't like to hunt their food during those hot hours4 ,frequently a turkey vulture sails majestically above the plains along the ,green ,river4 ,sometimes so high he appears to be a speck1 his telescopic eye searches the ground for the carrion upon which he feeds4 ,another bird that does not mind the heat is ,say's phoebe4 ,he is usually found perched on a fence post1 a wire1 or a dead branch waiting for some insect to buzz by4 ,a graceful1 short flight1 a pop of his beak1 and then back to his perch to repeat the cycle again4 ,as he sits motionless1 his gray breast and darker gray head and back make him hard to see4 ,the time to watch birds is in the evening2 as the sun sinks and the air cools1 they come forth4 ,small gray-brown rock wrens hop among the boulders near the visitor center4 ,robins scurry through the leaves in the stream course below the ,dinosaur ,quarry4 ,here too1 western flycatchers and ,audubon's warblers search among the cottonwoods for insects4 ,a flash of red and white is seen as a red-shafted flicker darts from its nest in the hollow trunk of a tree4 ,the sky is filled with wheeling1 twittering rough-winged swallows and white-throated swifts that descend from their nests on the cliffs to feed upon the gnats and other flying insects4 ,these are the birds that spend the spring and summer here4 ,they raise their families and1 young and old alike1 depart in autumn when frost kills the insects upon which they feed4 ,as they flee the cold of winter1 they are joined by many other birds that make their summer homes at higher elevations or more northern latitudes4 ,ducks1 geese1 and swans join the hordes moving southward4 ,so do the various shore birds1 bluebirds1 and hummingbirds4 ,but the sagebrush flats and brushy ravines are not left vacant by this wholesale migration1 for as the summer residents move out the winter residents move in4 ,the ,oregon and gray-headed juncos spend the entire winter here4 ,great flocks of mountain bluebirds descend from the mountains and pion jays make the hills resound with their screams4 ,canada geese and golden-eye ducks live on the ,green ,river and remain until it freezes4 ,the harsh croak of the raven is seldom heard in summer but often in winter4 ,few birds live here in winter and summer--the golden and bald eagles1 the red-tailed hawk1 and the little sparrow hawk4 ,perhaps the most handsome year-round resident is the magpie with its long1 iridescent tail1 black and white body1 and white patches on its wings4 ,one other resident makes his presence known by his eerie cry on frosty1 moonlit nights--the western horned owl4 ,he hunts every night1 summer and winter1 but is seldom seen4 ,occasionally he is disturbed upon his daylight roost and as he skillfully dodges through the junipers1 he makes a joke of the story that owls don't see well in daylight4 ,the mammals that live in the vicinity of the ,dinosaur ,quarry are almost never seen4 ,there are several reasons for this--almost all of them are nocturnal1 are very shy1 and most of them are small4 ,in spite of their retiring habits1 they reveal their presence in a number of ways4 ,patches of bare earth under sagebrush and nearby sandy slopes are crisscrossed with tiny paths beaten into the dust by deer mice4 ,along the river bank1 gnawed tree stumps1 a few fresh chips1 and perhaps a webbed footprint tell us beaver have been active during the night4 ,the paired hind footprints of the kangaroo rat are common on the hillside4 ,freshly fallen snow records the preceding night's activities in perfect detail4 ,illustration3 ,,golden-,,mantled ,,ground ,,squirrel ,were it not for the golden-mantled ground squirrels1 our evidence of mammals would be mostly indirect4 ,but these little fellows are very much in evidence all day long as they play around the visitor center and in the picnic areas4 ,they are handsome too1 with their alert black eyes1 cinnamon neck and shoulders1 and dark side patches with white stripes4 ,most people call these ground squirrels chipmunks because both are striped4 ,actually the two are easy to tell apart2 the chipmunk's stripes run to the tip of its nose1 but those of the golden-mantled ground squirrel extend forward only to the shoulder region4 ,any small1 striped mammal seen near the quarry is probably a ground squirrel1 as chipmunks are rare here4 ,the water problem is an ever-present one for the mammals as well as the plants4 ,at first this may seem strange with the ,green ,river so close and several springs in the hills1 but most of the smaller animals have very restricted ranges4 ,a deer mouse1 for example1 seldom travels more than #ajj feet from his home burrow in his entire lifetime4 ,the kangaroo rat and the desert woodrat also have limited ranges although theirs are somewhat larger than those of deer mice4 ,the majority of such animals must meet their water needs without springs and seeps4 ,how do they do it8 ,illustration3 ,,coyote4 7,,courtesy1 ,u4 ,s4 ,,fish ,,and ,,wildlife ,,service47 ,illustration3 ,,badger4 7,,courtesy1 ,u4 ,s4 ,,fish ,,and ,,wildlife ,,service47 ,the food they eat contains some water4 ,the green vegetation of springtime contains large amounts4 ,even air-dried foods such as seeds contain some4 ,and these animals don't need much4 ,through the thousands of years these little creatures have lived in arid lands1 evolutionary processes have altered their bodies and life patterns to fit the conditions under which they must live4 ,surely one of the most useful and interesting of their abilities is that of utilizing metabolic water4 ,such water is obtained through oxidation of hydrogen contained in food and is a by-product of metabolism4 ,putting it another way1 during the digestive process these animals are able to manufacture water from the chemical constituents of their food and the oxygen in their blood4 ,the amount of water thus obtained is between #gj and #ajj percent of the dry weight of the food eaten4 ,thus some desert animals are able to live a normal life span without ever taking a drink1 and probably many of them do4 ,carnivores such as the badger and the coyote get some of their water from the animals they eat and may go for days without visiting a spring4 ,but eventually they return to the river or a spring for a drink4 ,this is no special effort as carnivores generally range for miles in search of prey4 ,winter is a time of difficulty for most animals4 ,some of them like the ground squirrels hibernate and sleep the winter away1 but the majority must rustle their 8daily bread40 ,winter storms drive the mule deer down from the high country4 ,mice tunnel through the snow in search of food4 ,the white-tailed jackrabbit and the snowshoe hare change their coats from brown to white4 ,in particularly hard winters the animals die in great numbers1 first the weak and old1 then the young1 and sometimes even animals in prime condition fail to survive4 ,the reptiles that make their homes in the ,quarry ,area of ,dinosaur ,national ,monument are few in number4 ,the rattlesnake is rare and seldom seen4 ,the only common snake is the bull or gopher snake4 ,this snake can appear very threatening as it swells its body and hisses loudly1 but it is not poisonous4 ,gopher snakes climb well and are often seen in trees where they hunt for eggs and young birds4 ,two lizards are commonly seen here during the summer4 ,the side-blotched lizard is about #a to #b inches long with a somewhat longer tail4 ,these small brown lizards are frequently seen among the rocks near the parking and picnic areas4 ,the name1 side-blotched lizard1 is taken from the black or bluish-black area behind the foreleg of the males4 ,these lizards are also called brown utas4 ,the western whiptail is also a very common lizard4 ,as its name suggests1 it has a very long slender tail which it lashes from side to side as it runs4 ,this lizard is easily distinguished from the side-blotched lizard by its larger size1 longer more slender tail1 and the presence of bars and spots of black upon its back4 ,in late summer1 junior-sized young whiptails appear1 but their #c-;inch total length is unimpressive compared to #h-;inch adults4 ,the young are quite handsome with pleasing body colors and bright-blue tails4 ,often lizards are seen whose tails are missing4 ,when the tail is pulled or injured it can be shed by its owner4 ,the shed tail may wriggle for several minutes and attract the predator's attention while the lizard escapes4 ,the tailless lizard soon grows another one that is usually recognizable by its subdued or otherwise different color pattern4 ,sometimes the broken tail does not fall off so it and the new tail form a fork4 ,in summary then1 we see that this apparently lifeless desert does support a wide variety of living things and a great number of individuals4 ,some of them1 the plants and small animals1 live here all year round while others1 such as most birds1 live here only part of the time4 ,but whatever the length of stay1 all living things must adapt themselves to existing conditions at the time of their stay4 ,if they cannot adapt to static or changing conditions they must move or become extinct4 ,some #fj million years have passed since the dinosaurs ruled the world4 ,in that time mountains have risen1 wasted away1 and risen again4 ,glaciers have come and gone4 ,many species of plants and animals evolved and passed on to extinction4 ,every life form meets the test--adapt or die4 ,that test is as real to the dusty lizard basking on the quarry face as it was to the dinosaurs whose bones you came to see4 ,key to ,pronunciation ,dinosauria 7dy-noh-,,sawr-eea7 ,antrodemus 7an-troh-,,dee-mus7 ,apatosaurus 7apato-,,sawr-us7 ,ankylosaurus 7an-,,keeloh-sawr-us7 ,camptosaurus 7camp-toh-,,sawr-us7 ,stegosaurus 7steg-oh-,,sawr-us7 ,triceratops 7try-,,ser-a-tops7 ,archosauria 7,ark-oh-,,sawr-eea7 ,mesozoic 7,,mez-oh-zoh-ic7 ,triassic 7try-,,ass-ic7 ,jurassic 7jur-,,ass-ic7 ,cretaceous 7kre-,,tay-shus7 ,tyrannosaurus 7ty-ran-oh-,,sarh-us7 ,saurischia 7sawr-,,iss-key-a7 ,ornithischia 7orni-,,thiss-key-a7 ,diplodocus 7di-,,plod-icus7 ,camarasaurus 7camara-,,sawr-us7 ,protiguanodon 7pro-teeg-,,guan-oh-don7 ,suggested ,readings ,andrews1 ,roy ,chapman4 ,all ,about ,dinosaurs1 #adf pp4 ,random ,house1 ,new ,york4 ,a very interesting book about dinosaurs and the men who study them4 ,children1 #i-ab years old4 ,colbert1 ,edward ,h4 ,evolution of the ,vertebrates1 #dgi pp4 ,john ,wiley and ,sons1 ,inc41 ,new ,york4 #aiee4 ,a very readable account of vertebrate evolution for the student or serious amateur4 ---- ----4 ,dinosaurs1 #dth ed41 #cb pp4 ,american ,museum of ,natural ,history1 ,new ,york4 #aieg4 ,a good brief treatment of all dinosaurs4 ,excellent illustrations4 ,dunbar1 ,carl ,o4 ,historical ,geology1 #efg pp4 ,wiley1 ,new ,york4 #aidi4 ,an excellent treatment of earth's history and life from the beginning to the present4 ,life ,editorial ,staff4 ,the ,world ,we ,live ,in1 #cjd pp4 ,simon ,schuster1 ,new ,york4 #aiee4 ,elaborately illustrated book about the world's natural history4 ,transcriber's ,notes --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,in the text versions only1 text in italics is delimited by underscores4