02 The Badland Formations of the Black Hills Region 



tioned. Another one, dealing particularly with the later forms, 

 is by F. B. Loomis, Rhinocerotidae of the Lower Miocene. 

 Am. Jour. Sci., vol. 26, 1908, pp. 51-64. 



LOPHIODONTIDAE 



The lophiodonts, closely related to the ancestral tapirs, 

 are the most generalized of all the known perissodactyls. Prof. 

 Hayden, in 1886, found a small fragment of a jaw in the Big 

 Badlands, which Dr. Leidy in describing, referred to the Lophio- 

 dontidae, under the name Lophiodon (now Colo don) occiden- 

 talis. Later discoveries substantiated the correctness of this the 

 first determination of a lophiodon representative found in 

 America and added three additional species, namely, Colodon 

 procuspidatns, Colodon dakotensis, and Colodon longipes. The 

 first species was found in the Lower Oligocene. The last three, 

 identified by Osborn and Wortman, are from the Middle Oligo- 

 cene.* 



Fossils of Lophiodonts are found elsewhere in American 

 Tertiary, also in European Tertiary, but much of this material, 

 like that from the Big Badlands, is fragmentary. Nevertheless, 

 their greatly generalized nature as displayed in the material 

 studied, indicates a group of animals of great interest. Much 

 uncertainty prevails as to the exact relationships of the Lophio- 

 donts, but they are known to have many of the primitive char- 

 acters of the tapir, the hyracodont, and the horse. 



TAPIRS. 



The present day tapirs, like the horse, are the descendants 

 of a very ancient family. Unlike the horse, however, specializa- 

 tion in the tapir has not advanced to a high degree, and so far 

 as foot structure is concerned, and to a considerable extent tooth 

 structure also, the modern representatives of the tapir are in 

 much the same condition as the early ancestral horses. They are 

 very similar to the Lophiodonts *just described. Indeed, these 

 animals and the ancestral tapirs show so many characteristics 

 of such decided similarity or of such a vague nature as to render 

 their separation and classification a matter of difficulty and some 

 uncertainty. 



*Wortman, J. L., and Earl, Charles. Ancestors of the Tapir 

 from the Lower Miocene of Dakota. Bull. Am. Mus. Nat. Hist., Vol. 

 5, 1893, p,p. 159-180. 



Osborn, H. P., and, Wortman, J. L. Perissodactyls of the Lower 

 Miocene White River Beds. Bull. Am. Mus. Nat. Hist., Vol. 7, 1895, 

 pp. 343-3 75. 



