622 HISTORICAL GEOLOGY 



The order did not attain great importance until the Pliocene and Pleistocene, at 

 which time (p. 670) it assumed a leading role in South America. Some of the South 

 American edentates were the largest creatures on that continent. The description of 

 the South American sloths will be taken up in the discussion of Pleistocene mammals. 



True Carnivores. — When traced back, it is found that such dis- 

 tinct families as the dog, hyena, and cat become less and less easily 

 distinguished, until they converge in the primitive carnivores (Creo- 

 donta, p. 594) of the Eocene; and these, in turn, have affinities 

 with both insectivores and ancestral hoofed mammals (Condylarthra). 

 Before the close of the Oligocene many families of the true carnivores 

 appeared and lived in competition with the ancestral carnivores, 

 which they entirely replaced before the close of the Oligocene. 



In the Eocene and Oligocene primitive representatives of the 

 families to which belong the dog, weasel, cat, and hyena appeared ; 

 but the families were more clearly differentiated in the latter, at 

 which time ancestral dogs, raccoons, and weasels were common 

 although not yet of a distinctly modern type. In the epoch following 

 (Miocene) carnivores were abundant, and some of them so closely 

 resemble those of to-day that they have been included in the same 

 genera as living animals. Wolves, foxes, panther-like animals, 

 saber-toothed tigers, ancestral raccoons, as well as weasels and other 

 like forms were present. In Europe the bear and hyena were rep- 

 resented as well as the above. In the Pliocene carnivores flourished 

 and perhaps gained on the herbivores, forcing them to develop greater 

 speed, sagacity, and powers of defense. 



In South America during the Miocene there were no true carni- 

 vores ; but their place in nature was taken by carnivorous marsupials, 

 such as live in Australia to-day. 



Primates (Monkeys, Apes, Lemurs). — This order of mammals 

 has especial interest because it also includes man. The first known 

 members (lemurs) date back to the earliest Eocene deposits, where 

 their remains so closely resemble those of the generalized insec- 

 tivores of that early time that it is difficult to distinguish one from 

 the other. Monkeys and lemurs lived in North America during the 

 Eocene, but disappeared from this continent at the beginning of 

 the Miocene. Primate remains from the Miocene of France (Dryopi- 

 thecus) are of great interest because of the similarity in some respects 

 to the skeleton of man, and also because of the possibility that these 

 animals were able to make rough flint implements (eoliths, p. 675). 



How far it may be regarded as a stem from which on the one side 



