314 LAND MAMMALS IN THE WESTERN HEMISPHERE 



to a proper arrangement of the various species ; in essentials, 

 the forms all agreed and constituted several series of closely 



Fig. 163.' — t Titanothere (t Mesatirhinus superior) with long, narrow head ; Bridger 

 stage. Restored from a skeleton in the American Museum. 



allied genera. Comparing these Bridger animals with the 

 great ftitanotheres of the lower White River, the first and 

 most obvious difference that strikes the observer is the very- 

 much smaller size of the more ancient types. 

 With some variation in this respect, hardly 

 any of the Bridger species exceeded a modern 

 tapir in stature and very much resembled one 

 in proportions. The canine teeth were tusks 

 as large as those of a bear and must have been 

 very effective weapons ; the molar-pattern was 

 identical with that found in the great Oligocene 

 beasts, but the premolars were simpler and 

 relatively smaller. 

 The skull had a straight upper profile, though in several 

 of the phyla small bony protuberances were developed over 



Fig. 164. — Second 

 upper molar, right 

 side of a Bridger 

 ttitanothere 

 a Palceosyops) . 



