The Reptiles 



pores In their skin to help regulate the body temperature, and 

 changed their scales to hair and feathers. They began to 

 hatch their eggs within their bodies and to give birth to their 

 offspring. It must not be understood that the contempo- 

 raneous classes then living copied these new body functions 

 and adapted them to their present use — far from this. These 

 new developments furnished additional opportunities for 

 adaptation but all the new species that follow have sprung 

 from the parents that made the change. The other groups 

 have stayed In their own blind alley and failed to progress. 



The foundation structure for two new general classes — 

 that of the birds and mammals was now prepared. 



The birds are not directly descended from the leather 

 winged flying crocodiles, for their race is now extinct; but 

 instead, they have developed from a type of running or jump- 

 ing lizard that used only Its hind legs In running and chasing 

 Its food. They ran semi-upright using their forellmbs In a 

 flapping motion until they developed into wings. Their scales 

 became elongated and split up and developed into air cham- 

 bered feathers as an adaptation to their use. In the same 

 or similar manner, all their other bodily functions have devel- 

 oped to meet the conditions of their environment. 



[207] 



