220 



THE ORIGIN AND EVOLUTION OF LIFE 



In the final extinction of the herbivorous sauropod type we 

 find an example of the selection laiv of elimination^ attributable 



Fig. 98. .\\ii'iiiiiii 



i)R TlCKklCSrRID-lM.HXTATILE THEORY ( )i.' TiiK IlAliirS OF 



Apatosaurus. 



(Upper.) Apatosaurus { = Brontosaurus), a typical sauropod of Morrison age, quad- 

 rupedal, heavy-limbed, herbivorous, inhabiting the flood-plains (Morrison) and lagoons 

 of the region now elevated into the Rocky Mountain chain of Wyoming and Colorado. 



(Lower.) Mounted skeleton of Apatosaurus { = Brontosaimis) in the American Museum 

 of Natural History. 



to the fact that these types had reached a cul-de-sac of mechan- 

 ical evolution from which they could not adaptively emerge 



