r?i. 



THE NEW FOUR-TOED HORSE SKELETON 



By ir. D. Maiihvw 



THIS skeleton, presented by Mr. Frank K. Sturgis, represents the 

 earliest known stage in the ancestry of the horse. It was found in 

 1910 in the Wasatch formation of the Big Horn Basin of Wyoming. 



Three skeletons of the little four-toed horse of the Eocene period are 

 now on exhibition. The first, from the Wind River formation, was one of 

 the gems of the Cope collection, purchased by the Museum in 1894. The 

 second, found by the Museum expedition of 1905 in the Bridger Basin, 

 represents a later stage of evolution, the middle Eocene. This third skele- 

 ton, found at a lower geological horizon, is an earlier stage than the Cope 

 skeleton and although of somewhat larger size is more primitive in retaining 

 on the hind foot tiny splint-like vestiges of the first and fifth digits, reminis- 

 cences of an earlier five-toed condition which have been completely lost 

 by its successors. Although these vestigial splints are not preserved in 

 this skeleton, their existence is indicated by articulating facets on the 

 adjoining digits and in another partial skeleton of the sanu" sj)ecies found 

 in 191 1, one of the little splints is preserved entire. 



Numerous specimens of jaws and teeth of these little four-toed horses 

 have been secured by the persevering work of the American Mus(>um field 

 parties, but skeletons and skulls are exceedingly rare and this one, although 

 by no means complete, is somewhat more so than any hitherto found. 

 It has been restored and mounted in a grazing attitude by Albert Thomson. 



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