612 



The Animal Kingdo'm 



they share with some Hzards is the presence of a well-developed pineal 

 eye, complete with a retina. 



The Fossil Reptiles. — A history of the evolution of the animal 

 kingdom shows that during the various geologic eras, the different 

 groups had small beginnings, developed and diversified into dominant 



TO MAMMALS 



Fig. 203. — The family tree of the reptiles. (From Romer: Man and the 

 Vertebrates, The University of Chicago Press, Copyright, 1941, The University of 

 Chicago.) 



forms, and gradually disappeared. During the period of the greatest 

 development each group radiates in all directions and occupies all avail- 

 able habitats. Such has been the history of the reptiles. They began 

 as small, seemingly unimportant forms during the late Carboniferous, 



