30 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Figure 22. — Contours of the head and of parts of the mouth in browsing and grazing perissodactyls 



A, Asiatic rhinoceros {Rhinoceros ' inikusi, chiefly a browser; B, black rhinoceros ot Africa (R. (.Opsiceros) bicornis), chiefly a browser; C, white 

 rhinoceros of Africa (R. (Ccraioiherium) simum), chiefly a grazer; D, domestic horse {Equns caballus), chiefly a grazer; E, American 

 tapir ( Tapirus tenestTis), a browser. 



' The generic terminology of the rhinoceroses is not yet fully agreed upon by zoologists. The family tree, like that of the titanotheres, 

 is polyphyletic. 



