114 THE WHITE RIVER BADLANDS 



At the base of the beds the number of incisors is 

 from one to three on a side, while at the top there are 

 never more than two on a side, often only one, sometimes 

 none. In skulls from the very lowest beds the incisors have 

 already become so rudimentary as to be no longer func- 

 tional. As would be expected, the number of incisors de- 

 creased after they became of no functional value. In the 

 matter of incisors the Titanotheridae at the time of their 

 extermination, were in a fair way to accomplish just what 

 the somewhat related, but more persistent, Khinocerotidae 

 have nearly succeeded in doing, namely: the elimination of 

 the incisor dentition. In view of this weak frontal dentition 

 it would seem that for the securing of its food, the animal 

 must have been provided with a long tongue and a prehensile 

 lip. 



The Titanothers had their origin in early Eocene time, 

 were of considerable importance throughout the Bridger and 

 Uinta periods, reached their culmination during Lower Oli- 

 gocene time, and became wholly extinct at the close of the 

 latter period. ( See Fig. 53 ) . They present one of the most 

 interesting illustrations known of rapid evolution in size and 

 special characters followed by quick extinction. They de- 

 veloped slowly at first, and although they may be traced for 

 perhaps half a million years, they seem to have left abso- 

 lutely no descendants. Outside of North America the Titan- 

 otheres have been recognized only in Hungary and Bulgaria, 

 these latter localities have but one representative each. 



During the time of their greatest development the Titan- 

 otheres were the largest of all the mammals in the localities 

 where they lived. They were well prepared by size and of- 

 fensive weapons for combating the attacks of predaceous ani- 

 mals and they were possessors of perhaps the most efficient 

 dental equipment ever developed for masticating coarse vege- 

 table food, such as evidently flourished in abundance in the 

 region at that time. Their size was comparable to that of 

 the present day elephant, averaging slightly smaller. One of 

 the best known skeletons, that of Megacerops robustus found 

 in Corral Canyon and restored in 1895 by Osborn and Wort- 

 man of the American Museum of Natural History measures 

 thirteen feet, eight inches in length, seven feet, seven 

 inches in height, and breadth across the pelvis three feet, ten 



