FOSSIL ANIMALS 



333 



of huge size, as the massive 75-foot Brontosaiirus and the 10-ton Stego- 

 saiirus. Other points of interest concerning the Mesozoic are that tmc 

 mammals were in existence, recognizable from their teeth and jaws, and 

 the first birds appeared. 



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Fig. 279. — Permocaiboniferous reptile, Edaphosaurus cruciger; skeleton above, 

 restoration below. {From specimen in Museum of Geology, University of Michigan; restora- 

 tion by Prof. E. C. Case.) 



The outstanding feature of the Cenozoic is the tremendous develop- 

 ment of the mammals, which rivaled that of the reptiles in the Mesozoic. 

 No brief account can do them justice. The primitive members of this 

 group are the marsupials, represented in North America by the opossum, 

 which is little changed now from its Eocene form. Contrasted with these 

 were huge forms (7 or 8 feet high) with bony protuberances on the head, 



