92 



THE WHITE RIVER BADLANDS 



Figure 34 — Skull of Metamynodon planifrons. Osborn, 1896. 



Miocene time and in Europe from Eocene to Pliocene time. 

 There is much reason for believing that the rhinoceros 

 family originated in North America and subsequently spread 

 to the old world but this has not as yet been proven. 



All rhinoceroses, living and extinct, are divided by Os- 

 born into three subdivisions, as follows. The Hyracodonti- 

 dae or cursorial (upland) rhinoceroses; the Amynodontidae 

 (aquatic) rhinoceroses, and the Rhinocerotidae or true (low- 

 land) rhinoceroses. Of these the first two are found onlv in 



Figure 35 — Skull of Caenopus tridactylus. Osborn, 1898. 



