PREHISTORIC ANIMALS 



435 



The Rodentia have left remains throughout the Tertiary ; 

 many of their oldest fossils belong to existing genera, but several 

 families have become extinct. Both the Insectivora and the 

 Chiroptera are represented by fossils as early as the Eocene, 

 and the genera then living were very similar to those existing 

 to-day. 



The Carnivora are found throughout the Tertiary, but the 

 genera are all much less specialized than at present, and repre- 



FlG. 413. Dinotherium giganteum, a 

 gigantic extinct Proboscidean; side 

 view of skull, one fifteenth natural size. 

 (After Kaup, from Parker and Has- 

 well's Text-book.) 



sent conditions intermediate between the many sharply differen- 

 tiated genera existing to-day. Thus we find connecting links, 

 as it were, which join the dogs, bears, hyenas, and cats with one 

 another. The Pinnipedia do not appear until the middle and 

 more recent portions of the Tertiary ; sea lions are found in the 

 Miocene, seals and walruses in the Pliocene. 



The Primates appear in the Eocene where they are repre- 

 sented by the Lemuroidea. Remains of the Old World monkeys 

 are found in the Miocene and the Pliocene of Europe and Asia ; 

 there are species of both extinct and existing genera. Species 



