HERBIVOROUS DINOSAURS 



217 



quadrupedal mode of progression is revealed in the recently 

 described Plateosaiirus of Jaekel from the Trias of Germany 

 (Fig. 94), an animal which could progress either on two or on 

 four legs. 



The Sauropoda reached the climax of their evolution dur- 

 ing the close of Jurassic (Morrison formation) and the be- 



PALEOOEOGRftPHY. LOWER CRETACEOUS (UPPER NEOCOMIAN-VELANGIAN-HILS-WEALDEN 

 AFTER SCHUCHERT. APRIL 1918 

 »..^ MARINE DEPOSITS T; CONTINENTAL DEPOSITS \ SIERRA NEVADA 



ITY-MORISSON) 1 



Fig. 95. Theoretic World Environment in Lower Cretaceous Time. 



The dominant period of the great sauropod dinosaurs. This shows the theoretic South 

 Atlantic continent Gondwana connecting South America and Africa, and the Eurasiatic 

 Mediterranean sea Tclhys. Shortly afterward comes the rise of the modern flowering 

 plants and the hardwood forests. The shaded patch over the existing region of Wyo- 

 ming and Colorado is the flood-plain (Morrison) centre of the giant Sauropoda (see Fig. 

 97). After Schuchert, 1916. 



ginning of Cretaceous time (Comanchean Epoch). Meanwhile 

 they attained world-wide distribution, migrating throughout a 

 long stretch of the present Rocky Mountain region of North 

 America, into southern Argentina, into the Upper Jurassic of 

 Great Britain, France, and Germany, and into eastern Africa. 

 The last named region is the one most recently explored, and 



