104 



THE WHITE RIVER BADLANDS 



The abundance of the fossil remains and their wide- 

 spread distribution geologically and geographically, clearly 

 indicate that for ages members of the horse family ranged 

 oyer the country in countless numbers. They were numerous 

 in both North America and South America. Beginning, as 

 they evidently did, in the earliest Tertiary or late Cretaceous 

 in some generalized form of small height, probably no great- 

 er, according to Marsh, than a rabbit, they continued in 

 increasing size to individuals larger than the largest draft 

 horses of the present day. The earliest and the latest known 

 members of the family do not occur in the deposits described 

 in this paper, but intermediate forms are found in consider- 

 able numbers. These intermediate forms merit our chief at- 

 tention. 



WnSt 



Wast 



Figure 43 — Illustration to show evolution of the fore foot in the 

 Horse family. Osborn. 



With one exception all horses of the White Kiver bad- 

 lands had three toes on each foot. Those of the older for- 

 mations, particularly of the Oligocene, stand approximately 

 midway in the genealogical line and show characters of ab- 

 sorbing interest. 



It may be noted here that Eocene horses are four 

 toed, with short crowned teeth; Oligocene horses are three 



