SUCCESSIVE MAMMALIAN FAUNAS 235 



to which the middle toe (the third of the original five) had been 

 enlarged to carry the whole weight and the lateral toes (second 

 and fourth) reduced to mere ''dew-claws." While browsing 

 horses, with low-crowned teeth, still persisted in large numbers, 

 we find also the extremely interesting beginnings of the highly 

 complex, cement-covered and high-crowned teeth of the graz- 

 ing kinds. The clawed fchalicotheres were present, though 

 very little is known about them because of the fragmentary 

 character of the remains. 



The Artiodactyla were much more varied and abundant, 

 though they did not rival the great assemblage of these ani- 

 mals found in the European Miocene. Of the peccaries little 

 more can be said than that they were present in these faunas. 

 The joreodonts were very numerous, both individually and 

 generically ; two stages of the proboscis-bearing kind are found 

 here together, the older, long-faced genus {^Promerycochoerus) 

 surviving from the Oligocene, while the newer Miocene type was 

 short-faced and had a moderate proboscis (see Fig. 196, p. 373). 

 Others had more the proportions of peccaries and still others 

 were very small and presumably aquatic in habits. Camels 

 abounded, both the grazing kinds which were ancestral to 

 the modern forms of South America and Asia, and the great, 

 browsing fgirafTe-camels. The fhornless deer and the antlered 

 fdeer-antelopes were much like those of the Upper Miocene, 

 slender and graceful little creatures, and there were also con- 

 siderably larger ruminants {^Dromomeryx) with straight, simple 

 and non-deciduous horns, which may be called antelopes. 



The fine of division between the lower Miocene and the 

 uppermost Oligocene is a very obscure and difficult one to 

 draw. Personally, I prefer to begin the Miocene with the 

 widespread formation of the Great Plains, which has been 

 variously named Arikaree, Harrison, Rosebud, etc., but this 

 is a moot point. Concerning the lower part of these beds 

 Osborn says: "They may be either: (1) Upper OHgocene or 

 (2) transitional from Oligocene to Miocene, or (3) of pure 



