CARNIVOROUS DINOSAURS 



213 



88) is not inconsistent with the theory of a semi-arid climate 

 advocated by Barrell to explain the reddish continental de- 

 posits not only in the region of the Connecticut valley but 

 over the southwestern Great Plains. The flora of ferns, cycads, 

 and conifers indicates moderate conditions of temperature. 

 Along the Pacific coast there was a great overflow of the seas 

 along the western continental border and an archipelago of 

 volcanic islands. In this region there were numerous coral 

 reefs and an abundance of cephalopod ammonites. In the 



Fig. qi. A Carm\(jR(h:s Uknusaur Preying upon a Sauropou. 



Skeletons (left) and restoration (right) of the bipedal dinosaur Allosaunis of Upper Jurassic 

 and Lower Cretaceous time in the act of feeding upon the carcass of Apatosaitnis, one 

 of the giant herbivorous Sauropoda of the same period. Mounted specimens and 

 restoration by Osborn and Knight in the American Museum of Natural History. 



interior continental seas great marine reptiles (Cymbospondylus, 

 Fig. 82), related to the ichthyosaurs, were abundant. 



The primitive light-bodied, long-tailed type of dinosaur of 

 bipedal locomotion originates in this country with Marsh's 

 Anchisaurus of the Connecticut valley (Fig. 88) and develops 

 into the more powerful form of the Allosaurus of Marsh from 

 the Jurassic flood-plains east of the Rocky Mountains (Fig. 91). 

 Contemporaneous with this powerful animal is the much more 

 delicate Ornitholestes, which is departing from the carnivorous 

 habits of its ancestors and seeking some new form of food. It 

 is in turn ancestral to the remarkable "ostrich dinosaur" of 

 the Upper Cretaceous, Struthiomimus {Ornithomimus) , which 

 is bird-like both in the structure of its limbs and feet and in 



