SUCCESSIVE MAMMALI.1N FAUNAS 



269 



Of the archaic and extinct orders of hoofed animals, the 

 only one which persisted from earlier times into the Bridger 

 and greatly flourished there was the jAmblypoda, one family 

 of which (fUintatheriidse) was preeminently characteristic 

 of middle Eocene life, becoming very rare and then dying out 

 in the upper Eocene. The fuintatheres of the Bridger under- 

 went considerable modification in size and appearance within 



Fig. 139. — A mesonychid toreodont (iDromocyoii velox) of the Bridger stage. 

 Restored from a skeleton in the Museum of Yale University. 



the limits of the stage, the larger and stranger species appearing 

 toward the end of the time. Most of these great creatures 

 may fairly be called gigantic, for they equalled the largest 

 modern rhinoceroses and smaller elephants in size. The body, 

 limbs and feet were so elephantine in character that they 

 were once believed to be ancestral Proboscidea, but the teeth 

 and the fantastic skull were so radically different that this 

 belief was long ago abandoned. The upper canine teeth were 

 converted, in the males, into formidable spear-like or scimitar- 

 Uke tusks, protected by great flange-shaped expansions of the 



