^ THE NEW EVOLUTION 



history described on the analogy of a tree with a 

 close approximation to the known facts. 



Thus the reptiles first appeared in that very ancient 

 time known as the Carboniferous and gradually 

 branched out, increasing in diversity and in maximum 

 size. The largest land animals of which we have any 

 knowledge are the largest of the dinosaurs, which 

 flourished in the Jurassic and Cretaceous. At the 

 end of the Cretaceous period most of the larger and 

 more spectacular of the reptiles suddenly disappeared, 

 but many reptilian types, for instance the turtles, 

 lizards, snakes and crocodilians continued right 

 through to the present day. 



The mammals first appeared in the form of very 

 small and insignificant creatures at the time (Jurassic) 

 when the great reptiles were the dominating giants 

 of the land and sea. After the sudden disappearance 

 of the giant reptiles at the end of the Cretaceous, the 

 mammals increased greatly in diversity and somewhat 

 in size, though in the earlier portion of the epoch fol- 

 lowing (the Eocene) the largest mammal was not so 

 large even as a sheep. 



These mammals of the earlier portion of the "dawn 

 period" (Eocene) soon disappeared, but as they dis- 

 appeared their place was taken by other types which 

 were more or less comparable to the sorts we know 

 today. Gradually as time went on these mammals 

 became more and more diversified. Various extra- 

 ordinary types appeared, some of huge size and in 

 aspect most bizarre, while together with these came 

 others which we have no difficulty in recognizing as 



