In the museum at Yale College are collected the spoils of numerous expeditions to the West, and the many tons of bones lying there are believed to represent the remains of no less than two hundred individuals of the Dinocerata. So perfectly have these bones been preserved by Nature that, even if the creatures had been living now, the material for studying their skeletons could hardly be more complete. Professor Marsh recognises three distinct types in this strange group of quadrupeds, on each of which a genus has been founded. The first and oldest form is the Uintatherium, which takes its name from the Uinta Mountains. This, as might be expected, is the most primitive or least specialised form, and comes from lower strata. The most highly developed or specialised form is the Tinoceras, and this is found at the highest geological level or “horizon.”
Between these two extremes, and from an intermediate horizon, comes the Dinoceras,[41] so that in tracing these animals through the strata in which they occur the geologist finds that he is following for a while the course of their evolution. Doubtless there were many slight differences presented by the members of this group, but at present it has not been found possible to determine the number of species, although about thirty forms more or less distinct have been recognised. Professor Marsh says that the specimen of the skull of Dinoceras mirabile, on which the whole order Dinocerata was founded, is, fortunately, in a very perfect state of preservation, and that it belonged to a fully adult animal. Moreover, it was embedded in so soft a matrix that the brain-cavity and the openings leading from it could be worked out without difficulty. In removing the skull from the rock, on the high and almost inaccessible cliff where it was found, two or three important fragments were lost; but Professor Marsh, after a laborious search, recovered them from the bottom of a deep ravine, where they had been washed down and covered up.
[41] The Dinoceras of Marsh is the same form as Eobasileus of Cope. Uintatherium was discovered by Leidy.
It is about twenty-two years since the wonderful forms of life sealed up within these Eocene lake-deposits first became known to science. Long before then, however, the wandering Indian had been accustomed to seeing strange-looking skulls and skeletons that peeped out upon him from the sides of cañons and hills, as the rocks that enclosed them crumbled away under the influence of atmospheric agents of change—the ceaseless working of wind, rain, heat, and cold. To his untrained mind no other explanation suggested itself than the idea that these were the bones of his ancestors, which it would be highly impious to disturb. Requiescant in pace! So he left them in peace. Perhaps he believed in a former race of human giants; if so, these would be their bones. Long before Professor Marsh’s expeditions, the earliest squatters, trappers, and others used to bring back news of marvellous monsters grinning from the ledges of rock beneath which they camped. At last these tales attracted the notice of some enthusiastic naturalists in the eastern States. Professor Leidy obtained a number of bones, from which he was able to bring to light an extinct creature at that time unknown to science, namely, the Uintatherium. Professor Cope also described some extinct animals disinterred by himself from the same region.
But our knowledge of the Dinocerata is chiefly due to Professor Marsh, who has despatched one expedition after another, and who, after many years of laborious research both in the western deserts and in his wonderful collection at Yale College, has published a splendid monograph on the subject. No trouble and no expense have been spared in order to obtain material for this great work, and all geologists must feel grateful to Professor Marsh for so liberally devoting his time and his private resources in order to advance the science of Palæontology.
The region in which the remains occur of the remarkable group of extinct animals now under consideration, has a peculiar scenery of its own, unlike anything in Europe. The following graphic description of its features is from the pen of Sir Archibald Geikie:—[42]
[42] Nature, vol. xxxii. p. 97.
“On the high plateau that lies to the west of the Rocky Mountains, along the southern borders of the Wyoming territory, the traveller moving westwards begins to enter on peculiar scenery. Bare, treeless wastes of naked stone, rising here and there into terraced ledges and strange tower-like prominences, or sinking into hollows where the water gathers in salt or bitter pools. Under the cloudless sky, and in the clear dry atmosphere, the extraordinary colouring of these landscapes forms, perhaps, their weirdest feature. Bars of deep red alternate with strips of orange, now deepening into sombre browns, now blazing out again into vermilion, with belts of lilac, buff, pale green, and white. And everywhere the colours run in almost horizontal bands, running across hollows and river-gorges for mile after mile through this rocky desert. The parallel strips of colour mark the strata that cover all this wide plateau country. They are the tints characteristic of an enormous accumulation of sedimentary rocks, that mark the site of a vast Eocene lake, or succession of lakes, on what is now nearly the crest of the continent.”
In this strange region the flat-topped hills, table-lands, or terraces, as they are variously named, seen from lower levels, are usually called “buttes,” especially when they are of limited extent. This name is of French origin, and signifies a bank of earth or rising ground. It is also applied in a limited sense to the more prominent irregularities of the deeply sculptured slopes of the larger terraces. These buttes, therefore, vary in extent, from a mere mound rising slightly above the level of the plains to hills of varied configuration reaching to the level of the broader buttes or terraces.
The débris resulting from the continual wearing away, or demolition of these buttes and terraces, now lies spread out on the plains below. From the lower plains the smaller terraces appear like vast earth-work fortifications, and when not too much cut up by erosion, remind one of long railway embankments. But in many cases the terraces are so much cut up by narrow ravines that they appear as great groups of naked buttes rising from the midst of the plain. Nothing can be more desolate in appearance than some of these vast assemblages of crumbling buttes, destitute of vegetation, and traversed by ravines, in which the watercourses in midsummer are almost all dried up. To these assemblages of naked buttes, often worn into castellated and fantastic forms, and extending through miles and miles of territory, the early Canadian voyageurs gave the name Mauvais Terres. They occur in many localities of the Tertiary formations west of the Mississippi River. Professor Leidy, who with two friends made an expedition in search of fossils to Dry Creek Cañon in this region of the “Bad Lands,” about forty miles to the southeast of Fort Bridger (Wyoming), thus describes his impressions:—