FOSSIL ANIMALS 



335 



The lines of descent of modern elephants, horses, and cephalopods are 

 especially useful for illustration. 



Evolution of Elephants. — The mastodon-elephant series shows a 

 larger number of obvious changes than either of the other series named. 



Fig. 281. — Restoration of horned dinosaur Triceratops. {After Lull, from Schuchert, 

 "Historical Geology," John Wiley & Sons, Inc.) 



Figure 283 will disclose the more striking steps of their evolution. The 

 earliest animal recognized as belonging to the elephant series, Moeri- 

 therium by name, was recovered from late Eocene and early Oligocene 



Fig. 282. — Diagram of the fossil history of the major groups of vertebrate animals, 

 width of the bands indicates abundance and number of kinds. 



The 



deposits of northern Egypt. It was slightly over 3 feet in height. The 

 elephantine features are the high posterior portion of the skull (Fig. 283F') 

 composed of cancellate bone, that is, bone containing open spaces; the 



