82 THE ORIGIN OF MAN 



their introduction sounds the death knell of the 

 archaic forms, for one stock after another van- 

 ishes and most of them are gone before the close 

 of the Eocene. It is usually thought that the 

 modern mammals originated in Asia, although 

 we do not know for a certainty. A most striking 

 feature of the life of early Eocene time was the 

 appearance in considerable numbers of diminu- 

 tive horse-like forms, fleet-footed rhinoceroses, 

 tapirs, the first ruminants and pig-like forms, 

 squirrel-like rodents, insectivores, carnivores, 

 lemurs, monkeys and possibly also marsupial 

 opossums. It was in other words the mammalian 

 life of a mountainous country, superior in foot 

 and tooth structure to the indigenous archaic 

 fauna, and of a higher intelligence. In the later 

 Eocene, the changes were largely toward greater 

 size, more muscular power, and the origination 

 of new indigenous forms. There were many 

 hoofed animals and all were browsers. During 

 this period appeared tiny camels, true tapirs, 



