The Pamphlet Collection of Sir Robert Stout: Volume 31
Fossil Horses in America
Fossil Horses in America.
That knowledge has recently come to us, and assuredly from a most unexpected quarter. You are all aware that when this country was first discovered by Europeans there were found no traces of the existence of the horse in any part of the American Continent. And, as is well known, the accounts of the earlier discoverers dwell upon the astonishment of the natives when they first became acquainted with the astounding phenomenon—a man seated upon a horse. Nevertheless, as soon as geology began to be pursued in this country, it was found that remains of horses—horses like our European horses—like the horses which exist at the present day—are to be found in abundance in the most superficial deposits in this country, just as they are in Europe. For some reason or other—no feasible suggestion on that subject, so far as I know, has been made—but for some reason or other the horse must have died out on this Continent at some period preceding—how long we cannot say—the discovery of America by the Europeans. Of late years there have been discovered on this Continent—in your Western territories—that marvelous thickness of tertiary deposits to which I referred the other evening, which gives us a thickness and a consecutive order of tertiary rocks admirably calculated for the preservation of organic remains, such as we had hitherto no conception of in Europe. They have yielded fossils in a state of preservation and in number perfectly unexampled. And with respect to the horse, the researches of Leidy and others have shown that numerous forms of the fossil horse have existed among these remains. But it is only recently that the very admirably contrived and most thoroughly and patiently worked-out investigations of Professor Marsh have given us a just idea of the enormous wealth and scientific importance of these deposits. I have had the advantage of glancing over his collections at New Haven, and I can truly and emphatically say that, so far as my knowledge extends, there is nothing in any way comparable to them for extent, or for the care with which the remains have been got together, or for their scientific importance, to the series of fossils which he has brought together (Applause). That enormous collection has yielded evidence of the most striking character in regard to this question of the pedigree of the horse. And, indeed, the evidence which Professor Marsh has collected tends to show that you have in America the t rue original seat of the equine type—the country in which the evidence of the primitive lite and modification of the horse is far better preserved than in Europe; and Professor Marsh's kindness has enabled me to put before you this diagram, every figure in which is an actual representation of a specimen which is preserved in New Haven at this present time. The succession of forms which he has brought together shows, in the first place, the great care and patience to which I have referred. Secondly, there is this pliocene form of the horse (Pliohippus), the conformation of its limbs presents some very slight deviations from the ordinary horse, and with shorter crown of the grinding teeth. Then comes the form which represents the European Hipparion, which is the Protohippus, having three toes and the fore-arm and leg and teeth to which I have referred, and which is more valuable than the European Hipparion for this reason; it is devoid of some of the peculiarities of that form, peculiarities which tend to show that the European Hipparion is rather a side branch than one in the direct line of design. But next comes the form of Miohippus, which corresponds pretty nearly with what I mentioned as the Anchitherium of Europe, but which has some interesting peculiarities. It presents three toes—one large one and two lateral ones—and the fourth toe, which answers to the little finger of the human hand, but there is only a rudi- page 35 ment of this, as in the lateral toe of the horse. This is, however, as far as European deposits have been enabled to carry us with any degree of certainty in the history of the horse. In this American tertiary, on the contrary, the series is continued evenly down to the bottom of the eocene, and these older rocks yield these remains, The miocene form termed Mesohippus has three toes in front and a large splint for the rudiment representing the little finger, and three toes behind. The radius and ulna are entire and the tibia and fibula distinct, and there are simply anchitheroid short-crowned teeth.
But this is probably the most important discovery of all—the Orohippus—which comes from the oldest part of the eocene formation, and is the oldest one known. Here we have the four toes on the front-limb complete, three toes on the hind limb complete, a well-developed ulna, a well-developed fibula, and the teeth of simple pattern. So you are able, thanks to these great researches, to show that, so far as present knowledge extends, the history of the horse type is exactly and precisely that which could have been predicted from a knowledge of the principles of Evolution. And the knowledge we now possess justifies its completely in the anticipation that when the still lower eocene deposits and those which belong to the cretaceous epoch have yielded up their remains of equine animals, we shall find first an equine creature with four toes in front and a rudiment of the thumb. Then probably a rudiment of the fifth toe will be gradually supplied, until we come to the five-toed animals, in which most assuredly the whole series took its origin.