Fig. 36.: Ankylosaurus, top view of skull in fig. 35.After BrownFig. 36.—Ankylosaurus, top view of skull in fig. 35.
After Brown
Fig. 36.—Ankylosaurus, top view of skull in fig. 35.
This marvellous animal was made known to science by the discoveries of the Museum parties in Montana and Alberta under Barnum Brown. Fragmentary remains of smaller relatives had been discovered by earlier explorers but nothing that gave any adequate notion of its character or gigantic size. From a partial skeleton discovered in the Hell Creek beds of Montana, and others in the Edmonton and Belly River formations of the Red Deer River, Alberta, it has been possible to reconstruct the entire skeleton of the animal, save for the feet, and to locate and arrange most of the armor plates exactly. A skeleton mount from these specimens will shortly be constructed for the Cretaceous Dinosaur Hall.
Scelidosaurus, Polacanthus, etc.Various armored dinosaurs, of smaller size and less heavily plated, have been described from the Jurassic, Comanchic and Cretacic formations of Europe. The best known areScelidosaurusof the Lower Jurassic of England, andPolacanthusof the Comanchic (Wealden).Stegopeltaof the Cretaceous of Wyoming is more nearly related toAnkylosaurus.
Sub-Order Ceratopsia.
In 1887 Professor Marsh published a brief notice of what he supposed to be a fossil bison horn found near Denver, Colorado. Two years later the explorations of the lamented John B. Hatcher in Wyoming and Montana resulted in the unexpected discovery that this horn belonged not to a bison but to a gigantic horned reptile, and that it belonged not in the geological yesterday as at first thought, but in the far back Cretacic, millions of years ago. For Mr. Hatcher found complete skulls, and later secured skeletons, clearly of the Dinosaurian group, but representing a race of dinosaurs whose existence, or at least their extraordinary character, had been quite unsuspected. It appeared indeed that certain teeth and skeleton bones previously discovered by Professor Cope were related to this new type of dinosaur, but the fragments known to the Philadelphia professor gave him no idea of what the animal was like, although with his usual acumen he had discerned that they differed from any animal known to science and registered them as newunder the names ofAgathaumas1873 andMonoclonius1876. Professor Marsh re-named his supposed bison "Ceratops" (i.e."horned face") and gave to the closely related skulls discovered by Mr. Hatcher the name ofTriceratops(i.e."three horned face"), while to the whole group he gave the name of Ceratopsia.
Fig. 37.: Skulls of Horned Dinosaurs.Fig. 37.—Skulls of Horned Dinosaurs. The lower row,Ceratops,Styracosaurus,Monoclonius, are from the Middle Cretacic (Belly River formation) of Alberta;Anchiceratopsis from the Upper Cretacic (Edmonton formation) of Alberta;TriceratopsandTorosaurusfrom the uppermost Cretacic (Lance formation) of Wyoming.
Fig. 37.—Skulls of Horned Dinosaurs. The lower row,Ceratops,Styracosaurus,Monoclonius, are from the Middle Cretacic (Belly River formation) of Alberta;Anchiceratopsis from the Upper Cretacic (Edmonton formation) of Alberta;TriceratopsandTorosaurusfrom the uppermost Cretacic (Lance formation) of Wyoming.
These were the first of a long series of discoveries which through scientific and popular descriptions have made the Horned Dinosaurs familiar to the world.Most of them are still very imperfectly known, and of their evolution and earlier history we know very little as yet. But we can form a fairly correct idea of their general appearance and habits and of the part they played in the world of the late Cretacic. So far as known they were limited to North America. The most striking feature of the Horned Dinosaurs is the gigantic skull, armed with a pair of horns over the orbits and a median horn on the nasal bones in front, and with a great bony crest projecting at the back and sides. In some species the skull with its bony frill attains a length of seven or even eight feet and about three feet width; the usual length is five or six feet and the width about three. In the best known genus,Triceratops, the paired horns are long and stout and the front horn quite short or almost absent, while inMonocloniusthese proportions are reversed, the front horn being long while the paired horns are rudimentary.
The teeth are in a single row but are broadened out into a wide grinding surface. The animal was quadrupedal, with short massive limbs and rounded elephantine feet tipped with hoofs, three in the hind foot, four in the fore foot, a short massive tail that could hardly reach the ground, a short broad-barrelled body and a short neck completely hidden on top and sides by the overhanging bony frill of the skull. In many respects these animals are suggestive far more than any other dinosaurs, of the great quadrupeds of Tertiary and modern times, rhinoceroses, hippopotami,titanotheres and elephants, as in the horns they suggest the bison. For this reason although less gigantic than the Brontosaurus or Tyrannosaurus, less grotesque perhaps, than the Stegosaurus, they are more interesting than any other dinosaurs. While thus departing far from the earlier type of the beaked dinosaurs (the Iguanodonts) they are evidently descended from them.
Fig. 38.: Skull of Triceratops from the Lance formation in Wyoming.Fig. 38.—Skull ofTriceratopsfrom the Lance formation in Wyoming, one-eighteenth natural size. The length of the horns is 2 feet, 9½ inches. The rostral bone or beak, and the lower jaw, are lacking; in the illustration on the cover they have been restored in outline. This fine skull was discovered by George M. Sternberg, and purchased for the Museum by Mr. Charles Lanier in 1909.
Fig. 38.—Skull ofTriceratopsfrom the Lance formation in Wyoming, one-eighteenth natural size. The length of the horns is 2 feet, 9½ inches. The rostral bone or beak, and the lower jaw, are lacking; in the illustration on the cover they have been restored in outline. This fine skull was discovered by George M. Sternberg, and purchased for the Museum by Mr. Charles Lanier in 1909.
This is the best known of the Horned Dinosaurs, as various skulls and partial skeletons have been found from which it has been possible to reconstruct the entire animal. There is a mounted skeleton in the National Museum, another will shortly be mounted in the American Museum, and there are skulls in several American and European museums.
Triceratopsexceeded the largest rhinoceroses in bulk, equalling a fairly large elephant, but with much shorter legs. The great horns over the eyes projected forward or partly upward; in one of our skulls they are 33½ inches long. During life they were probably covered with horn increasing the length by six inches or perhaps a foot. The ball-like condyle for articulation of the neck lies far underneath, at the base of the frill, almost in the middle of the skull.
Fig. 39.: Skull of Monoclonius, a horned dinosaur from the Cretacic (Belly River formation) of Alberta.Fig. 39.—Skull ofMonoclonius, a horned dinosaur from the Cretacic (Belly River formation) of Alberta. One-fifteenth natural size. The horns over the eyes are rudimentary, and the nasal horn large, reversing the proportions inTriceratops.
Fig. 39.—Skull ofMonoclonius, a horned dinosaur from the Cretacic (Belly River formation) of Alberta. One-fifteenth natural size. The horns over the eyes are rudimentary, and the nasal horn large, reversing the proportions inTriceratops.
Monoclonius, Ceratops, etc.TheTriceratopsand another equally gigantic Horned Dinosaur,Torosaurus, were the last survivors of their race. In somewhat older formations of Cretacic age are found remainsof smaller kinds, some of them ancestors of these latest survivors, others collaterally related. None of these have the bony frill completely roofing over the neck as it does inTriceratops. There is always a central spine projecting backwards and widening out at the top to the bony margin of the frill which sweeps around on each side to join bony plates that project from the sides of the skull top. This encloses an open space or "fenestra," so that the neck was not completely protected above. Sometimes the margin of the frill is plain, at other times it carries a number of great spikes, like a gigantic Horned Lizard (Phrynosoma).
Fig. 40.: Outline sketch restoration of Triceratops, from the mounted skeleton in the National Museum.Fig. 40.—Outline sketch restoration ofTriceratops, from the mounted skeleton in the National Museum.
Fig. 40.—Outline sketch restoration ofTriceratops, from the mounted skeleton in the National Museum.
InCeratopsthe horns over the eyes are large and the nasal horn small. InMonocloniusthe nasal horn is large and those over the eyes are rudimentary. The great variety of species that has been found in recent years shows that these Horned Dinosaurs were anumerous and varied race of which as yet we know only a few. Of their evolution we have little direct knowledge, but probably they are descended from the Iguanodonts and Camptosaurs of the Comanchic, and their quadrupedal gait, huge heads, short tails and other peculiarities are secondary specializations, their ancestors being bipedal, long-tailed, small headed and hornless.
The fine skulls ofTriceratops,Monoclonius,CeratopsandAnchiceratopsin the Museum collections illustrate the variety of these remarkable animals. Complete skeletons of the first two genera are being prepared for mounting and exhibition.
Remains of Dinosaurs have been found in all the continents, but chiefly in Europe and North America. Explorations in other parts of the world have not as yet been sufficient to show whether or not each continent developed especial kinds peculiar to it, nor to afford any reliable evidence as to whether the relations of the continents were different during the Mesozoic. Thus far, the Carnivorous group seems most widespread, for it alone has been found in Australia. The Sauropods or Amphibious Dinosaurs have been found in Europe, North America, India, Madagascar, Patagonia, and Africa, sufficient to show that their distribution was world wide with the possible exception of Australia, and probable exception of most oceanic islands (few of the modern oceanic islands existed at that time although there may well have been many others no longer extant). The Beaked Dinosaurs are more limited in their distribution, for none of them so far as at present known reached Australia or South America. But in the present stage of discovery it would be rash to conclude that they were surely limited to the regions wherethey have been discovered. It is not wholly clear as yet whether the Dinosaurian fauna that flourished at the end of the Jurassic in the north survived to the Upper Cretacic in the southern continents, but present evidence points that way, and indicates that the girdle of ocean which during the Cretacic depression encircled the northern world, formed a barrier which the Cretacic dinosaurian fauna never succeeded in crossing.
The earlier groups of Beaked Dinosaurs are found in both Europe and America, and in the Cretacic the Duck-billed and Armored groups are represented in both regions. The Horned Dinosaurs, however, are known with certainty only from North America.
While most of the important fossil specimens in this country have been found in the West, more fragmentary remains have been found on the Atlantic sea-board, and it is probable that they ranged all over the intervening region, wherever they found an environment suited to their particular needs.
The visitor who is introduced to the dinosaurs through the medium of books and pictures or of the skeletons exhibited in the great museums, finds it hard—well nigh impossible—to realize their existence. However willing he may be to accept on faith the reconstructions of the skeletons, the restorations of the animals and their supposed environment, it yet remains to him somewhat of a fairy-tale, a fanciful imaginative world peopled with ogres and dragons and belonging to the unreal "once upon a time" which has no connection with the ever present workaday world in which we live. Birds and squirrels, rabbits and foxes belong to this real world because he has seen them in his walks through the woods; even elephants and rhinoceroses, though his acquaintance be limited to menagerie specimens, seem fairly real—although one recalls the farmer's comment on first seeing a giraffe in the Zoological park: "There aint no sich animal." But dinosaurs—one easily realizes the state of mind that prompts the inquiry so often made by visitors to the Dinosaur Hall:—"they make these out of plaster, don't they?" So far as is consistent with good taste, theaim of the American Museum has been to enable the visitor to see for himself how much of plaster reconstruction there is to each skeleton, and to explain in the labels what the basis was for the reconstructed parts.
How They are Found.But to the collector these extinct animals are real enough. As he journeys over the western plains he sees the various living inhabitants thereof, birds and beasts, as well as men, pursuing their various modes of life; here and there he comes across the scattered skeletons or bones of modern animals lying strewn upon the surface of the ground or half buried in the soil of a cut bank. In the shales or sandstones that underlie the soil he finds the objects of his search, skeletons or bones of extinct animals, similarly disposed, but buried in rock instead of soft soil, and exposed in cañons and gullies cut through the solid rock. Each rock formation, he knows by precept and experience, carries its own peculiar fauna, its animals are different from those of the formation above and from those in the formation below. Days and weeks he may spend in fruitless search following along the outcrop of the formation, through rugged badlands, along steep cañon walls, around isolated points or buttes, without finding more than a few fragments, but spurred on by vivid interest and the rainbow prospect of some new or rare find. Finally perhaps, after innumerable disappointments, a trail of fragments leads up to a really promising prospect. A cautious investigation indicates that an articulated skeleton is buriedat this point, and that not too much of it has "gone out" and rolled in weathered fragments down the slope. For the tedious and delicate process of disinterring the skeleton from the rock he will need to keep ever in mind the form and relations of each bone, the picture of the skeleton as it may have been when buried. The heavy ledges above are removed with pick and shovel, often with help of dynamite and a team and scraper. As he gets nearer to the stratum in which the bones lie the work must be more and more careful. A false blow with pick or chisel might destroy irreparably some important bony structure. Bit by bit he traces out the position and lay of the bones,working now mostly with awl and whisk-broom, uncovering the more massive portions, blocking out the delicate bones in the rock, soaking the exposed surfaces repeatedly with thin "gum" (mucilage) or shellac, channeling around and between the bones until they stand out on little pedestals above the quarry floor. Then, after the gum or shellac has dried thoroughly and hardened the soft parts, and the surfaces of bone exposed are further protected by pasting on a layer of tissue paper, it is ready for the "plaster jacket." This consists of strips of burlap dipped in plaster-of-paris and pasted over the surface of each block until top and sides, all but the pedestal on which it rests, are completely cased in, the strips being pressed and kneaded close to the surface of the block as they are laid on. When this jacket sets and dries the block is rigid and stiff enough to lift and turn over; the remains of the pedestal are trimmed off and the under surface is plastered like the rest. With large blocks it is often necessary to paste into the jacket, on upper or both sides, boards, scantling or sticks of wood to secure additional rigidity. For should the block "rack," or become shattered inside, even though no fragments were lost, the specimen would be more or less completely ruined.
Fig. 41.: A Dinosaur skeleton, prospected and ready for encasing in plaster bandages and removal in blocks.Fig. 41.—A Dinosaur skeleton, prospected and ready for encasing in plaster bandages and removal in blocks. (Corythosaurus, Red Deer River, Alberta.)
Fig. 41.—A Dinosaur skeleton, prospected and ready for encasing in plaster bandages and removal in blocks. (Corythosaurus, Red Deer River, Alberta.)
The next stage will be packing in boxes with straw, hay or other materials, hauling to the railway and shipment to New York.
Arrived at the Museum, the boxes are unpacked,each block laid out on a table, the upper side of its plaster jacket softened with water and cut away, and the preparation of the bone begins. Always it is more or less cracked and broken up, but the fragments lie in their natural relations. Each piece must be lifted out, thoroughly cleaned from rock and dirt, and the fractured surfaces cemented together again. Parts of bones, especially the interior, are often rotted into dust while the harder outer surface is still preserved. The dust must be scraped out, the interior filled with a plaster cement, and the surface pieces re-set in position. Very often a steel rod is set into the plaster filling the interior of a bone, to secure additional strength.
After this preparation is completed, each part being soaked repeatedly with shellac until it will absorb no more, the bones can be handled and laid out for study or exhibition. Then, if they are to be mounted for a fossil skeleton, comes the work of restoring the missing parts. For this a plaster composition is used.
Where only parts of one side are missing the corresponding parts of the other side are used for model; where both sides are missing, other individuals or nearly related species may serve as a guide. But it is seldom wise to attempt restoration of a skeleton unless at least two-thirds of it is present; composite skeletons made up of the remains of several or many individuals, have been attempted, but they are dangerous experiments in animals so imperfectly known as are most ofthe dinosaurs. There is too much risk of including bones that pertain to other species or genera, and of introducing thereby into the restoration a more or less erroneous concept of the animal which it represents. The same criticism applies to an overly large amount of plaster restoration.
Fig. 42.: Bone-Cabin Draw on Little Medicine River north of Medicine Bow, Wyoming.Fig. 42.—Bone-Cabin Draw on Little Medicine River north of Medicine Bow, Wyoming. The location of the quarry is indicated by the stack of crated specimens on the left, and close to it the low sod-covered shack where the collecting party lived. Beyond the draw lies the flat rolling surface of the Laramie Plains and on the southern horizon the Medicine Bow Range with Elk Mountain at the center.
Fig. 42.—Bone-Cabin Draw on Little Medicine River north of Medicine Bow, Wyoming. The location of the quarry is indicated by the stack of crated specimens on the left, and close to it the low sod-covered shack where the collecting party lived. Beyond the draw lies the flat rolling surface of the Laramie Plains and on the southern horizon the Medicine Bow Range with Elk Mountain at the center.
In some instances the missing parts of a skeleton are not restored, because, even though but a small part be gone, we have no good evidence to guide in its reconstruction. This gives an imperfect and sometimes misleading concept of what the whole skeleton was like, but it is better than restoring it erroneously. Usually with the more imperfect skeletons, a skull, a limb or some other characteristic parts may be placed on exhibition but the remainder of the specimen is stored in the study collections.
Fig. 43.: American Museum party at Bone-Cabin Quarry, 1899. Seated, left to right Walter Granger, Professor H.F. Osborn, Dr. W.D. Matthew; standing, F. Schneider, Prof. R.S. Lull, Albert Thomson, Peter Kaison.Fig. 43.—American Museum party at Bone-Cabin Quarry, 1899. Seated, left to right Walter Granger, Professor H.F. Osborn, Dr. W.D. Matthew; standing, F. Schneider, Prof. R.S. Lull, Albert Thomson, Peter Kaison.
Fig. 43.—American Museum party at Bone-Cabin Quarry, 1899. Seated, left to right Walter Granger, Professor H.F. Osborn, Dr. W.D. Matthew; standing, F. Schneider, Prof. R.S. Lull, Albert Thomson, Peter Kaison.
Where They are Found.The chief dinosaur localities in this country are along the flanks of the Rocky Mountains and the plains to the eastward, from Canada to Texas. Not that dinosaurs were any more abundant there than elsewhere. They probably ranged all over North America, and different kinds inhabited other continents as well. But in the East and the Middle West, the conditions were not favorable for preservingtheir remains, except in a few localities. Formations of this age are less extensive, especially those of the delta and coast-swamps which the dinosaurs frequented. And where they do occur, they are largely covered by vegetation and cannot be explored to advantage. In the arid Western regions these formations girdle the Rockies and outlying mountain chains for two-thousand miles from north to south, and are extensively exposed in great escarpments, river cañons and "badland" areas, bare of soil and vegetation and affording an immense stretch of exposed rock for the explorer. Much of this area indeed is desert, too far away from water to be profitably searched under present conditions, or too far away from railroads to allow of transportation of the finds at a reasonable expense. Fossils are much more common in certain parts of the region, and these localities have mostly been explored more or less thoroughly. But the field is far from being exhausted. New localities have been found and old localities re-explored in recent years, yielding specimens equal to or better than any heretofore discovered. And as the railroad and the automobile render new regions accessible, and the erosion of the formations by wind and rain brings new specimens to the surface, we may look forward to new discoveries for many years to come.
In other continents, except in Europe, there has been but little exploration for dinosaurs. Enough is known to assure us that they will yield faunæ no less extensiveand remarkable than our own. We are in fact only beginning to appreciate the vast extent and variety of these records of a past world.
In a preceding chapter it was shown that the chief formations in which dinosaur remains have been found belong to the end of the Jurassic and the end of the Cretacic periods. The Jurassic dinosaur formations skirt the Rockies and outlying mountain ranges but are often turned up on edge and poorly exposed, or barren of fossils. The richest collecting ground is in the Laramie Plains, between the Rockies and the Laramie range in south-central Wyoming, but important finds have also been made in Colorado and Utah. The Cretaceous Dinosaur formations extend somewhat further out on the plains to the eastward, and the best collecting regions thus far explored are in eastern Wyoming, central Montana and in Alberta, Canada.
By Prof. S.W. Williston.
Most great discoveries are due rather to a state of mind, if I may use such an expression, than to accident. The discovery of the immense dinosaur deposits in the Rocky Mountains in March, 1877, may truthfully be called great, for nothing in paleontology has equalled it, and that it was made by three observers simultaneously can not be called purely an accident. Thesediscoverers were Mr. O. Lucas, then a school teacher, later clergyman; Professor Arthur Lakes, then a teacher in the School of Mines at Golden, Colorado; and Mr. William Reed, then a section foreman of the Union Pacific Railroad at Como, Wyoming, later the curator of paleontology of the University of Wyoming—even as I write this, comes the notice of his death,—the last. I knew them all, and the last two were long intimate friends.
In the autumn of 1878 I wrote the following:[19]
"The history of their discovery (the dinosaurs) is both interesting and remarkable. For years the beds containing them had been studied by geologists of experience, under the surveys of Hayden and King, but, with the possible exception of the half of a caudal vertebra, obtained by Hayden and described by Leidy as a species ofPoikilopleuron, not a single fragment had been recognized. This is all the more remarkable from the fact that in several of the localities I have observed acres literally strewn with fragments of bones, many of them extremely characteristic and so large as to have taxed the strength of a strong man to lift them. Three of the localities known to me are in the immediate vicinity, if not upon the actual townsites of thriving villages, and for years numerous fragments have been collected by (or for) tourists and exhibited as fossil wood. The quantities hitherto obtained, thoughapparently so vast, are wholly unimportant in comparison with those awaiting the researches of geologists throughout the Rocky Mountain region. I doubt not that many hundreds of tons will eventually be exhumed." Rather a startling prophecy to make within eighteen months of their discovery, but it was hardly exaggerated.
It is impossible to say which of these three observers actually made the first discovery of Jurassic dinosaurs; whatever doubt there is is in favor of Mr. Reed.
Professor Lakes, accompanied by his friend Mr. E.L. Beckwith, an engineer, was, one day in March, 1877, hunting along the "hogback" in the vicinity of Morrison, Colorado, for fossil leaves in the Dakota Cretaceous sandstone which caps the ridge, when he saw a large block of sandstone with an enormous vertebra partly imbedded in it. He discussed the nature of the fossil with his friend (so he told me) and finally concluded that it was a fossil bone. He had recently come from England and had heard of Professor Phillips' discoveries of similar dinosaurs there. He knew of Professor Marsh of Yale from his recent discoveries of toothed birds in the chalk of Kansas, and reported the find to him. As a result, the specimen, rock and all, was shipped to him by express at ten cents a pound! And Professor Marsh immediately announced the discovery ofTitanosaurus(Atlantosaurus)immanis, a huge dinosaur having a probable length of one hundred and fifteen feet andunknown height. And Professor Lakes was immediately set at work in the "Morrison quarry" near by, whence comes the accepted name of these dinosaur beds in the Rocky Mountains. Professor Lakes once showed me the exact spot where he found his first specimen.
Mr. Lucas, teaching his first term of a country school that spring in Garden Park near Cañon City, as an amateur botanist was interested in the plants of the vicinity. Rambling through the adjacent hills in search of them, in March, 1877, he stumbled upon some fragments of fossil bones in a little ravine not far from the famous quarry later worked for Professor Marsh. He recognized them as fossils and they greatly excited, not only his curiosity, but the curiosity of the neighbors. He had heard of the late Professor Cope and sent some of the bones to him, who promptly labelled themCamarasaurus supremus.
The announcement of these discoveries promptly brought Mr. David Baldwin, Professor Marsh's collector in New Mexico, to the scene. Only a few months previously he had discovered fossil bones in the red beds of New Mexico, the since famous Permian deposits. He naturally explored the same beds at Cañon City, immediately below the dinosaur deposits, and soon found the still very problematicalHallopusskeleton, at their very top, a specimen which after nearly forty years remains unique of its kind.
A few years earlier Professor Marsh, on his way east from the Tertiary deposits of western Wyoming, hadstopped at Como, Wyoming, to observe the strange salamanders, or "fish with legs" as they were widely known, so abundant in the lake at that place, about whose transformations he later wrote a paper, perhaps the only one on modern vertebrates that he ever published. While he was there Mr. Carlin, the station agent, showed him some fossil bone fragments, so Mr. Reed told me, that they had picked up in the vicinity, and about which Professor Marsh made some comments. But he was so engrossed with the other discoveries he was then making that he did not follow up the suggestion. Had he done so the discovery of the "Jurassic Dinosaurs" would have been made five years earlier.
Fig. 44.: The first dinosaur specimen found at Bone-Cabin Quarry. Hind limb of Diplodocus.Fig. 44.—The first dinosaur specimen found at Bone-Cabin Quarry. Hind limb ofDiplodocus.
Fig. 44.—The first dinosaur specimen found at Bone-Cabin Quarry. Hind limb ofDiplodocus.
Mr. Reed, tramping over the famous Como hills after game—he had been a professional hunter of game for the construction camps of the Union Pacific Railroad—in the winter and spring of 1877, observed some fossil bones just south of the railway station that excited his curiosity. But he and Mr. Carlin did not make their discovery known to Professor Marsh till the following autumn, and then under assumed names, fearing that they would be robbed of their discovery. I was sent to Como in November of 1877 from Cañon City. I got off the train at the station after midnight, and enquired for the nearest hotel—(the station comprised two houses only), and where I could find Messrs. Smith and Robinson. I was told that the section house was the only hotel in the place and that thesegentlemen lived in the country and that there was no regular bus-line yet running to their ranch. A freshly opened box of cigars, however, helped clear up things, and I joined Mr. Reed the next day in opening "Quarry No. 1" of the Como hills. Inasmuch as the mercury in the thermometer during the next two months seldom reached zero—upward I mean—the opening of this famous deposit was made under difficulties. That so much "head cheese," as we called it, was shipped to Professor Marsh was more the fault of the weather and his importunities than our carelessness. However, we found some of the types of dinosaurs that have since become famous.
I joined Professor Lakes at the Morrison quarry in early September of 1877, and helped dig out some of the bones ofAtlantosaurus. A few weeks later I was sent to Cañon City to help Professor Mudge, my old teacher, and Mr. Felch, who had begun work there in the famous "Marsh Quarry". It was here that we found the type ofDiplodocus.
The hind leg, pelvis and much of the tail of this specimen lay in very orderly arrangement in the sandstone near the edge of the quarry, but the bones were broken into innumerable pieces. After consultation we decided that they were too much broken to be worth saving—and so most of them went over into the dump. Sacrilege, doubtless, the modern collector will say, but we did not know much about the modern methods of collecting in those days, and moreover we were in toomuch of a hurry to get the new discoveries to Yale College to take much pains with them. I did observe that the caudal vertebrae had very peculiar chevrons, unlike others that I had seen, and so I attempted to save some samples of them by pasting them up with thick layers of paper. Had we only known of plaster-of-paris and burlap the whole specimen might easily have been saved. Later, when I reached New Haven, I took off the paper and called Professor Marsh's attention to the strange chevrons. AndDiplodocuswas the result.
My own connection with the discoveries of these old dinosaurs continued only through the following summer, in Wyoming, when we added the first mammals from the hills immediately back of the station, and the types of some of the smaller dinosaurs, and when we explored the vicinity for other deposits, on Rock Creek and in the Freeze Out Mountains.
How many tons of these fossils have since been dug up from these deposits in the Rocky Mountains is beyond computation. My prophecy of hundreds of tons has been fulfilled; and they are preserved in many museums of the world.
S.W. Williston.
By Henry Fairfield Osborn.
One is often asked the questions: "How do you find fossils?" "How do you know where to look for them?" One of the charms of the fossil-hunter's life is the variety, the element of certainty combined with the gambling element of chance. Like the prospector for gold, the fossil-hunter may pass suddenly from the extreme of dejection to the extreme of elation. Luck comes in a great variety of ways: sometimes as the result of prolonged and deliberate scientific search in a region which is known to be fossiliferous; sometimes in such a prosaic manner as the digging of a well. Among discoveries of a highly suggestive, almost romantic kind, perhaps none is more remarkable than the one I shall now describe.
Discovery of the Great Dinosaur Quarry.In central Wyoming, at the head of a "draw," or small valley, not far from the Medicine Bow River, lies the ruin of a small and unique building, which marksthe site of the greatest "find" of extinct animals made in a single locality in any part of the world. The fortunate fossil-hunter who stumbled on this site was Mr. Walter Granger of the American Museum expedition of 1897.
In the spring of 1898, as I approached the hillock on which the ruin stands, I observed, among the beautiful flowers, the blooming cacti, and the dwarf bushes of the desert, what were apparently numbers of dark-brown boulders. On closer examination, it proved that there is really not a single rock, hardly even a pebble, on this hillock; all these apparent boulders are ponderous fossils which have slowly accumulated or washed out on the surface from a great dinosaur bed beneath. A Mexican sheep-herder had collected some of these petrified bones for the foundations of his cabin, the first ever built of such strange materials. The excavation of a promising outcrop was almost immediately rewarded by finding a thigh-bone nearly six feet in length which sloped downward into the earth, running into the lower leg and finally into the foot, with all the respective parts lying in the natural position as in life. This proved to be the previously unknown hind limb of the great dinosaurDiplodocus.
In this manner the "Bone-Cabin Quarry" was discovered and christened. The total contents of the quarry are represented in the diagram (not reprinted.) It has given us, by dint of six successive years of hard work, the materials for an almost complete revival ofthe life of the Laramie region as it was in the days of the dinosaurs. By the aid of workmen of every degree of skill, by grace of the accumulated wisdom of the nineteenth century, by the constructive imagination, by the aid of the sculptor and the artist, we can summon these living forms and the living environment from the vasty deep of the past.
The Famous Como Bluffs.The circumstances leading up to our discovery serve to introduce the story. From 1890 to 1897 we had been steadily delving into the history of the Age of Mammals, in deposits dating from two hundred thousand to three million years back, as we rudely estimate geological time. In the course of seven years such substantial progress had been made that I decided to push into the history of the Age of Reptiles also, and, following the pioneers, Marsh and Cope, to begin exploration in the period which at once marks the dawn of mammalian life and the climax of the evolution of the great amphibious dinosaurs.
In the spring of 1897 we accordingly began exploration in the heart of the Laramie Plains, on the Como Bluffs. On arrival, we found numbers of massive bones strewn along the base of these bluffs, tumbled from their stratum above, too weather-worn to attract collectors, and serving only to remind one of the time when these animals—the greatest, by far, that nature has ever produced on land—were monarchs of the world.
Aroused from sleep on a clear evening in camp bythe heavy rumble of a passing Union Pacific freight-train[21], I shall never forget my meditations on the contrast between the imaginary picture of the great Age of Dinosaurs, fertile in cycads and in a wonderful variety of reptiles, and the present age of steam, of heavy locomotives toiling through the semi-arid and partly desert Laramie Plains.
So many animals had already been removed from these bluffs that we were not very sanguine of finding more; but after a fortnight our prospecting was rewarded by finding parts of skeletons of the long-limbed dinosaurDiplodocusand of the heavy-limbed dinosaurBrontosaurus. The whole summer was occupied in taking these animals out for shipment to the East, the so-called "plaster method" of removal being applied with the greatest success. Briefly, this is a surgical device applied on a large scale for the "setting" of the much-fractured bones of a fossilized skeleton. It consists in setting great blocks of the skeleton, stone and all, in a firm capsule of plaster subsequently reinforced by great splints of wood, firmly drawn together with wet rawhide. The object is to keep all the fragments and splinters of bone together until it can reach the skilful hands of the museum preparator.
The Rock Waves Connecting the Bluffs and the Quarry.The Como Bluffs are about ten miles south of theBone-Cabin Quarry; between them is a broad stretch of the Laramie Plains. The exposed bone layer in the two localities is of the same age, and originally was a continuous level stratum which may be designated as the "dinosaur beds;" but this stratum, disturbed and crowded by the uplifting of the not far-distant Laramie range of mountains and the Freeze Out Hills, was thrown into a number of great folds or rock waves. Large portions, especially of the upfolds, or "anticlines," of the waves, have been subsequently removed by erosion; the edges of these upfolds have been exposed, thus weathering out their fossilized contents, while downfolds are still buried beneath the earth for the explorers of coming centuries.
Therefore, as one rides across the country to-day from the bluffs to the quarry, startling the intensely modern fauna, the prong-horn antelopes, jack-rabbits, and sage-chickens, he is passing over a vast graveyard which has been profoundly folded and otherwise shaken up and disturbed. Sometimes one finds the bone layer removed entirely, sometimes horizontal, sometimes oblique, and again dipping directly into the heart of the earth. This layer (dinosaur beds) is not more than two hundred and seventy-four feet in thickness, and is altogether of fresh-water origin; but as a proof of the oscillations of the earth-level both before and after this great thin sheet of fresh-water rock was so widely spread, there are evidences of the previous invasion ofthe sea (ichthyosaur beds) and of the subsequent invasion of the sea (mosasaur beds) in the whole Rocky Mountain region.
In traveling through the West, when once one has grasped the idea of continental oscillation, or submergence and emergence of the land, of the sequence of the marine and fresh-water deposits in laying down these pages of earth-history, he will know exactly where to look for this wonderful layer-bed of the giant dinosaurs; he will find that, owing to the uplift of various mountain-ranges, it outcrops along the entire eastern face of the Rockies, around the Black Hills, and in all parts of the Laramie Plains; it yields dinosaur bones everywhere, but by no means so profusely or so perfectly as in the two famous localities we are describing.
How the Skeletons Lie in the Bluffs and Quarry.At the bluffs single animals lie from twenty to one hundred feet apart; one rarely finds a whole skeleton, such as that of Marsh'sBrontosaurus excelsus, the finest specimen ever secured here, which is now one of the treasures of the Yale museum. More frequently a half or a third of a skeleton lies together.
Fig. 45.: Collecting Dinosaurs at Bone-Cabin Quarry.Fig. 45.—Collecting Dinosaurs at Bone-Cabin Quarry.a. The overlying soil and rocks are loosened with a pick and removed with team and scraper down to the fossil layer.b. The fossil layer is carefully prospected with small tools, chisels, awls and whisk brooms exposing the bones as they lie in the rocks.c. The blocks containing the fossils are channelled around, plastered over top and sides, undercut and carefully turned over and the under side trimmed and plastered.d. The blocks are then packed in boxes or crates with hay or any other available packing material.e. Boxes are loaded on wagons and hauled across country to the railroad.f. Boxes are finally loaded on cars and shipped through to New York City.
Fig. 45.—Collecting Dinosaurs at Bone-Cabin Quarry.
a. The overlying soil and rocks are loosened with a pick and removed with team and scraper down to the fossil layer.b. The fossil layer is carefully prospected with small tools, chisels, awls and whisk brooms exposing the bones as they lie in the rocks.c. The blocks containing the fossils are channelled around, plastered over top and sides, undercut and carefully turned over and the under side trimmed and plastered.d. The blocks are then packed in boxes or crates with hay or any other available packing material.e. Boxes are loaded on wagons and hauled across country to the railroad.f. Boxes are finally loaded on cars and shipped through to New York City.
a. The overlying soil and rocks are loosened with a pick and removed with team and scraper down to the fossil layer.
b. The fossil layer is carefully prospected with small tools, chisels, awls and whisk brooms exposing the bones as they lie in the rocks.
c. The blocks containing the fossils are channelled around, plastered over top and sides, undercut and carefully turned over and the under side trimmed and plastered.
d. The blocks are then packed in boxes or crates with hay or any other available packing material.
e. Boxes are loaded on wagons and hauled across country to the railroad.
f. Boxes are finally loaded on cars and shipped through to New York City.
In the Bone-Cabin Quarry, on the other hand, we came across a veritable Noah's-ark deposit, a perfect museum of all the animals of the period. Here are the largest of the giant dinosaurs closely mingled with the remains of the smaller but powerful carnivorous dinosaurs which preyed upon them, also those of the slow andheavy-moving armored dinosaurs of the period, as well as of the lightest and most bird-like of the dinosaurs. Finely rounded, complete limbs from eight to ten feet in length are found, especially those of the carnivorous dinosaurs, perfect even to the sharply pointed and recurved tips of their toes. Other limbs and bones are so crushed and distorted by pressure that it is not worth while removing them. Sixteen series of vertebræ were found strung together; among these were eight long strings of tail-bones. The occurrence of these tails is less surprising when we come to study the important and varied functions of the tail in these animals, and the consequent connection of the tail-bones by means of stout tendons and ligaments which held them together for a long period after death. Skulls are fragile and rare in the quarry, because in every one of these big skeletons there were no fewer than ninety distinct bones which exceeded the head in size, the excess in most cases being enormous.
The bluffs appear to represent the region of an ancient shoreline, such conditions as we have depicted in the restoration ofBrontosaurus(fig. 22)—the sloping banks of a muddy estuary or of a lagoon, either bare tidal flats or covered with vegetation. Evidently the dinosaurs were buried at or near the spot where they perished.
The Bone-Cabin Quarry deposit represents entirely different conditions. The theory that it is the accumulation of a flood is, in my opinion, improbable, becausea flood would tend to bring entire skeletons down together, distribute them widely, and bury them rapidly. A more likely theory is that this was the area of an old river-bar, which in its shallow waters arrested the more or less decomposed and scattered carcasses which had slowly drifted down-stream toward it, including a great variety of dinosaurs, crocodiles, and turtles, collected from many points up-stream. Thus were brought together the animals of a whole region, a fact which vastly enhances the interest of this deposit.
The Giant Herbivorous Dinosaurs.By far the most imposing of these animals are those which may be popularly designated as the great or giant dinosaurs. The name, derived fromdeinosterrible, andsauroslizard, refers to the fact that they appeared externally like enormous lizards, with very long limbs, necks, and tails. They were actually remotely related to the tuatera lizard of New Zealand, and still more remotely to the true lizards.
No land animals have ever approached these giant dinosaurs in size, and naturally the first point of interest is the architecture of the skeleton. The backbone is indeed a marvel. The fitness of the construction consists, like that of the American truss-bridge, in attaining the maximum of strength with the minimum of weight. It is brought about by dispensing with every cubic millimeter of bone which can be spared without weakening the vertebræ for the various stresses and strains to which they were subjected, and these musthave been tremendous in an animal from sixty to seventy feet in length. The bodies of the vertebræ are of hour-glass shape, with great lateral and interior cavities; the arches are constructed on the T-iron principle of the modern bridge-builder, the back spines are tubular, the interior is spongy, these devices being employed in great variety, and constituting a mechanical triumph of size, lightness, and strength combined. Comparing a great chambered dinosaurian (Camarasaurus) vertebra (see above) with the weight per cubic inch of an ostrich vertebra, we reach the astonishing conclusion that it weighed only twenty-one pounds, or half the weight of a whale vertebra of the same bulk. The skeleton of a whale seventy-four feet in length has recently been found by Mr. F.A. Lucas of the Brooklyn Museum to weigh seventeen thousand nine hundred and twenty pounds. The skeleton of a dinosaur of the same length may be roughly estimated as not exceeding ten thousand pounds.
Proofs of Rapid Movements on Land.Lightness of skeleton is a walking or running or flying adaptation, and not at all a swimming one; a swimming animal needs gravity in its skeleton, because sufficient buoyancy in the water is always afforded by the lungs and soft tissues of the body. The extraordinary lightness of these dinosaur vertebræ may therefore be put forward as proof of supreme fitness for the propulsion of an enormous frame during occasional incursions uponland[22]. There are additional facts which point to land progression, such as the point in the tail where the flexible structure suddenly becomes rigid, as shown in the diagram of vertebræ below; the component joints are so solid and flattened on the lower surface that they seem to demonstrate fitness to support partly the body in a tripodal position like that of a kangaroo. I have therefore hazarded the view that even some of these enormous dinosaurs were capable of raising themselves on their hind limbs, lightly resting on the middle portion of the tail. In such a position the animal would have been capable not only of browsing among the higher branches of trees, but of defending itself against the carnivorous dinosaurs by using its relatively short but heavy front limbs to ward off attacks.
There are also indications of aquatic habits in some of the giant dinosaurs which render it probable that a considerable part of their life was led in the water. One of these indications is the backward position of the nostrils. Many, but not all, water-living mammals and reptiles have the nostrils on top of the head, in order to breathe more readily when the head is partly immersed. Another fact of note, although perhaps less conclusive, is the fitness of the tail for use while moving about in the water, if not in rapid swimming.
The great tail, measuring from twenty-eight to thirty feet, was one of the most remarkable structures in these animals, and undoubtedly served a great variety ofpurposes, propelling while in the water, balancing and supporting and defending while on land. InDiplodocusit was most perfectly developed from its muscular base to its delicate and whip-like tip, perhaps for all these functions.
The Three Kinds of Giant Dinosaurs.It is very remarkable that three distinct kinds of these great dinosaurs lived at the same time in the same general region, as proved by the fact that their remains are freely commingled in the quarry.
What were the differences in food and habits, in structure and in gait, which prevented that direct and active competition between like types in the struggle for existence which in the course of nature always leads to the extermination of one or the other type? In the last three years we have discovered very considerable differences of structure which make it appear that these animals, while of the same or nearly the same linear dimensions, did not enter into direct competition either for food or for territory.
The dinosaur namedDiplodocusby Marsh is the most completely known of the three. Our very first discovery in the Bone-Cabin Quarry gave us the hint thatDiplodocuswas distinguished by relatively long, slender limbs, and that it may be popularly known as the "long-limbed dinosaur." The great skeleton found in the Como Bluffs enabled me to restore for the first time the posterior half of one of these animals estimated as sixty feet in length, the hips and tail especially beingin a perfect state of preservation. A larger animal, nearer seventy feet in length, including the anterior half of the body, and still more complete, was discovered about ten miles north of the quarry, and is now in the Carnegie Museum in Pittsburg. Combined, these two animals have furnished a complete knowledge of the great bony frame. The head is only two feet long, and is, therefore, small out of all proportion to the great body. The neck measures twenty-one feet four inches, and is by far the longest and largest neck known in any animal living or extinct. The back is relatively very short, measuring ten feet eight inches. The vertebræ of the hip measure two feet and three inches. The tail measures from thirty-two to forty feet. We thus obtain, as a moderate estimate of the total length of the animal, sixty-eight to seventy feet. The restored skeleton, published by Mr. J.B. Hatcher in July, 1901, and partly embodying our results, gave to science the first really accurate knowledge of the length of these animals, which hitherto had been greatly overestimated. The highest point in the body was above the hips; here in fact, was the center of power and motion, because, as observed above, the tail fairly balanced the anterior part of the body.
The restoration by Mr. Knight is drawn from a very careful model made under my direction, in which the proportions of the animal are precisely estimated. It is, I think, accurate—for a restoration—as well as interesting and up-to-date. These restorations arethe "working hypotheses" of our science; they express the present state of our knowledge, and, being subject to modification by future discoveries, are liable to constant change.
By contrast, the second type of giant dinosaur, theBrontosaurus, or "thunder saurian" of Marsh, as shown in the restoration (fig. 22), was far more massive in structure and relatively shorter in body. Five more or less complete skeletons are now to be seen in the Yale, American, Carnegie, and Field Columbian museums. In 1898 we discovered in the bluffs, about three miles west of the Bone-Cabin Quarry, the largest of these animals which has yet been found; it was worked out with great care and is now being restored and mounted complete in the American Museum. The thigh-bone is enormous, measuring five feet eight inches in length, and is relatively of greater mass than that ofDiplodocus. The neck, chest, hips, and tail are correspondingly massive. The neck is relatively shorter, however, measuring eighteen feet, while inDiplodocusit measures over twenty-one feet. The total length of this massive specimen is estimated at sixty-three feet, or from six to eight feet less than the largest "long-limbed" dinosaur. The height of the skeleton at the hips is fifteen feet. There is less direct evidence that the "thunder saurian" had the power of raising its fore quarters in the air than in the case of the "light-limbed saurian," because no bend or supporting point in the tail has been distinctly observed.
The third type of giant dinosaur is the less completely known "chambered saurian," theCamarasaurusof Cope orMorosaurusof Marsh, an animal more quadrupedal in gait or walking more habitually on all fours, like the greatCetiosaurus, or "whale saurian," discovered near Oxford, England. With its shorter tail and heavier fore limbs, it is still less probable that this animal had the power of raising the anterior part of its body from the ground. Of a related type, perhaps, is the largest dinosaur ever found; this is theBrachiosaurus, limb-bones of which were discovered in central Colorado in 1901 and are now preserved in the Field Columbian Museum of Chicago. Its thigh-bone is six feet eight inches in length, and its upper arm-bone, or humerus, is even slightly longer.
Feeding Habits of the Giant Dinosaurs.We still have to solve one of the most perplexing problems of fossil physiology; how did the very small head, provided with light jaws, slender and spoon-shaped teeth confined to the anterior region, suffice to provide food for these monsters? I have advanced the idea that the food ofDiplodocusconsisted of some very abundant and nutritious species of water-plant; that the clawed feet were used in uprooting such plants, while the delicate anterior teeth were employed only for drawing them out of the water; that the plants were drawn down the throat in large quantities without mastication, since there were no grinding or back teeth whatever in this animal. Unfortunately for thistheory, it is now found that the front feet were not provided with many claws, there being only a single claw on the inner side. Nevertheless by some such means as this, these enormous animals could have obtained sufficient food in the water to support their great bulk.
The Carnivorous Dinosaurs.Mingling with the larger bones in the quarry are the more or less perfect remains of swamp turtles, of dwarf crocodiles, of the entirely different group of plated dinosaurs, orStegosauria, but especially of two entirely distinct kinds of large and small flesh-eating dinosaurs. The latter rounded out and gave variety to the dinosaur society, and there is no doubt that they served the savage but useful purpose, rendered familiar by the doctrine of Malthus, of checking overpopulation. These fierce animals had the same remote ancestry as the giant dinosaurs, but had gradually acquired entirely different habits and appearance.
Far inferior in size, they were superior in agility, exclusively bipedal, with very long, powerful hind limbs, upon which they advanced by running or springing, and with short fore limbs, the exact uses of which are difficult to ascertain. Both hands and feet were provided with powerful tearing claws. On the hind foot is the back claw, so characteristic of the birds, which during the Triassic period left its faint impression almost everywhere in the famous Connecticut valley imprints of these animals. That the fore limb and hand were of some distinct use is proved by theenormous size of the thumb-claw; while the hand may not have conveyed food to the mouth, it may have served to seize and tear the prey. As to the actual pose in feeding, there can be little doubt as to its general similarity to that of theRaptoresamong the birds, as suggested to me by Dr. Wortman (see fig. 10); one of the hind feet rested on the prey, the other upon the ground, the body being further balanced or supported by the vertebræ of the tail. The animal was thus in a position to apply its teeth and exert all the power of its very powerful arched back in tearing off its food. That the gristle of the bone or cartilage was very palatable is attested not only by the toothmarks upon these bones, but by many similar markings found in the Bone-Cabin Quarry.
The Bird-Catching Dinosaur.Of all the bird-like dinosaurs which have been discovered, none possesses greater similitude to the birds than the gem of the quarry, the little animal about seven feet in length which we have namedOrnitholestes, or the "bird-catching dinosaur." It was a marvel of speed, agility, and delicacy of construction. Externally its bones are simple and solid-looking, but as a matter of fact they are mere shells, the walls being hardly thicker than paper, the entire interior of the bone having been removed by the action of the same marvelous law of adaptation which sculptured the vertebræ of its huge contemporaries. There is no evidence, however, that these hollow bones were filledwith air from the lungs, as in the case of the bones of birds. The foot is bird-like; the hand is still more so; in fact, no dinosaur hand has ever before been found which so closely mimics that of a bird in the great elongation of the first or index-finger, in the abbreviation of the thumb and middle finger, and in the reduction of the ring-finger. These fingers, with sharp claws, were not strong enough for climbing, and the only special fitness we have been able to imagine is that they were used for the grasping of a light and agile prey (see figs. 17, 18.)
Another reason for the venture of designating this animal as the "bird-catcher" is that the Jurassic birds (not thus far discovered in America, but known from theArchæopteryxof Germany) were not so active or such strong fliers as existing birds; in fact, they were not unlike the little dinosaur itself. They were toothed, long-tailed, short-armed, the body was feathered instead of scaled; they rose slowly from the ground. This renders it probable that they were the prey of the smaller pneumatic-built dinosaurs such as the present animal.
This hypothetical bird-catcher seems to have been designed to spring upon a delicately built prey, the structure being the very antipode of that of the large carnivorous dinosaurs. A difficulty in the bird-catching theory, namely, that the teeth are not as sharp as one would expect to find them in a flesh-eater, is somewhat offset by the similarity of the teeth to those ofthe bird-eating monitor lizards (Varanus), which are not especially sharp.
The Great Yield of the Quarry.Our explorations in the quarry began in the spring of 1898, and have continued ever since during favorable weather. The total area explored at the close of the sixth year was seven thousand two hundred and fifty square feet. Not one of the twelve-foot squares into which the quarry was plotted lacked its covering of bones, and in some cases the bones were two or three deep. Each year we have expected to come to the end of this great deposit, but it still yields a large return, although we have reason to believe that we have exhausted the richest portions.
We have taken up four hundred and eighty-three parts of animals, some of which may belong to the same individuals. These were packed in two hundred and seventy-five boxes, representing a gross weight of nearly one hundred thousand pounds. Reckoning from the number of thigh-bones, we reach, as a rough estimate of the total, seventy-three animals of the following kinds: giant herbivorous dinosaurs, 44; plated herbivorous dinosaurs, or stegosaurs, 3; iguanodonts or smaller herbivorous dinosaurs, 4; large carnivorous dinosaurs, 6; small carnivorous dinosaurs, 3; crocodiles, 4; turtles, 5. But this represents only a part of the whole deposit, which we know to be of twice the extent already explored, and these figures do not include the boneswhich were partly washed out and used in the construction of the Bone-Cabin. The grand total would probably include parts of over one hundred giant dinosaurs.
The Struggle for Existence Among the Dinosaurs.Never in the whole history of the world as we now know it have there been such remarkable land scenes as were presented when the reign of these titanic reptiles was at its climax. It was also the prevailing life-picture of England, Germany, South America, and India. We can imagine herds of these creatures from fifty to eighty feet in length, with limbs and gait analogous to those of gigantic elephants, but with bodies extending through the long, flexible, and tapering necks into the diminutive heads, and reaching back into the equally long and still more tapering tails. The four or five varieties which existed together were each fitted to some special mode of life; some living more exclusively on land, others for longer periods in the water.
The competition for existence was not only with the great carnivorous dinosaurs, but with other kinds of herbivorous dinosaurs (the iguanodonts), which had much smaller bodies to sustain and a much superior tooth mechanism for the taking of food.
The cutting off of this giant dinosaur dynasty was nearly if not quite simultaneous the world over. The explanation which is deducible from similar catastrophes to other large types of animals is that a very large frame, with a limited and specialized set of teeth fittedonly to a certain special food, is a dangerous combination of characters. Such a monster organism is no longer adaptable; any serious change of conditions which would tend to eliminate the special food would also eliminate these great animals as a necessary consequence.