Dinosaurs Part 6

CHAPTER IX.

THE BEAKED DINOSAURS (Concluded.)

D. THE HORNED DINOSAURS, TRICERATOPS, ETC.

_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 ac.u.men he had discerned that they differed from any animal known to science and registered them as new under the names of _Agathaumas_ 1873 and _Monoclonius_ 1876. 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 of _Triceratops_ (_i.e._ "three horned face"), while to the whole group he gave the name of Ceratopsia.

[Ill.u.s.tration: Fig. 37.--Skulls of Horned Dinosaurs. The lower row, _Ceratops_, _Styracosaurus_, _Monoclonius_, are from the Middle Cretacic (Belly River formation) of Alberta; _Anchiceratops_ is from the Upper Cretacic (Edmonton formation) of Alberta; _Triceratops_ and _Torosaurus_ from 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 in _Monoclonius_ these 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 ma.s.sive limbs and rounded elephantine feet tipped with hoofs, three in the hind foot, four in the fore foot, a short ma.s.sive 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, t.i.tanotheres 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.

[Ill.u.s.tration: Fig. 38.--Skull of _Triceratops_ from the Lance formation in Wyoming, one-eighteenth natural size. The length of the horns is 2 feet, 9-1/2 inches. The rostral bone or beak, and the lower jaw, are lacking; in the ill.u.s.tration 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.]

TRICERATOPS.

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.

_Triceratops_ exceeded 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 33-1/2 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.

[Ill.u.s.tration: Fig. 39.--Skull of _Monoclonius_, 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 in _Triceratops_.]

_Monoclonius, Ceratops, etc._ The _Triceratops_ and another equally gigantic Horned Dinosaur, _Torosaurus_, were the last survivors of their race. In somewhat older formations of Cretacic age are found remains of 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 in _Triceratops_.

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 s.p.a.ce 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_).

[Ill.u.s.tration: Fig. 40.--Outline sketch restoration of _Triceratops_, from the mounted skeleton in the National Museum.]

In _Ceratops_ the horns over the eyes are large and the nasal horn small. In _Monoclonius_ the 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 a numerous 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 of _Triceratops_, _Monoclonius_, _Ceratops_ and _Anchiceratops_ in the Museum collections ill.u.s.trate the variety of these remarkable animals. Complete skeletons of the first two genera are being prepared for mounting and exhibition.

CHAPTER X.

GEOGRAPHICAL DISTRIBUTION OF DINOSAURS.

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 where they have been discovered. It is not wholly clear as yet whether the Dinosaurian fauna that flourished at the end of the Jura.s.sic 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.

CHAPTER XI.

COLLECTING DINOSAURS.

HOW AND WHERE THEY ARE FOUND.

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, the aim 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 canons 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 canon walls, around isolated points or b.u.t.tes, 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 buried at 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 sc.r.a.per. 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 ma.s.sive portions, blocking out the delicate bones in the rock, soaking the exposed surfaces repeatedly with thin "gum" (mucilage) or sh.e.l.lac, channeling around and between the bones until they stand out on little pedestals above the quarry floor. Then, after the gum or sh.e.l.lac 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.

[Ill.u.s.tration: 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 s.h.i.+pment 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 sc.r.a.ped 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 sh.e.l.lac 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 of the 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.

[Ill.u.s.tration: 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.

[Ill.u.s.tration: 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 preserving their 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 canons 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 a.s.sure us that they will yield faunae no less extensive and 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 Jura.s.sic and the end of the Cretacic periods. The Jura.s.sic 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.

THE FIRST DISCOVERY OF DINOSAURS IN THE WEST.