84 THE ORIGIN OF MAN 



they vanished their place was taken by dogs and 

 later by wolves and first sabre-tooth cats; true 

 cats, however, were not yet present. At the time 

 of the Miocene period there were large numbers 

 of horses, camels, ruminants and rodents with 

 high-crowned, persistently growing, grinding 

 teeth. There were also four-tusked, browsing, 

 long-faced mastodons, the short-legged rhinocer- 

 oses, the cats, and beavers. The most prominent 

 of the Miocene mammals were the horses, which 

 roamed^ the plains in great herds. All were 

 three-toed and at first all were still browsers, but 

 later in the Miocene the grazing type predomi- 

 nated. Likewise the camels were plentiful and 

 rhinoceroses were present in great variety, some 

 hornless, others with a single horn on the end of 

 the nose, and still others with an additional horn 

 on the forehead. Peccaries abounded, and the 

 last of the giant pigs, the entelodonts, were pres- 

 ent, one of them, in the Lower Pliocene, being 

 over six feet tall. The first true deer appeared 



