THE EVIDENCE FOR ORGANIC EVOLUTION 



517 



ancestral to the elephants of the present day is another example 

 of a relatively complete fossil record (Fig. 278). 



The earliest known representative of the elephant family appears 

 in the rocks of the late Eocene in the Libyan desert of Africa. 

 Types that are believed to have descended from this one may 

 be traced to all the other continents except Australia. In this 

 progenitor, Moeritherium, there is no proboscis, and the head has 



Fig. 277. — Comparison of stages in evolution of forelimb of horse with 



human hand. 



(Photo, by courtesy American Museum of Natural History.) 



no obvious resemblance to that of a modern elephant. In passing 

 through the series the snout becomes elongated to form the pro- 

 boscis; the jaws become shortened, in the line of descent that gave 

 rise to the present-day elephants; the teeth become modified; 

 and there is a great increase in size of body and of the brain. 

 Like the horses, the elephants became extinct at the close of the 

 Pleistocene in Europe and North America, where the mammoths 

 and mastodons, which are members of the elephant family, had 

 ranged widely during epochs when the family was in its most 



