The Story of the Rocks 



127 



Some of the dinosaurs browsed on the abundant vegetation 

 of lake and river shore, while others were eaters of flesh and 

 may have preyed upon their weaker brethren or fed upon 

 their decaying carcasses. 



Unfortunately for the dinosaur and vice v&sa for their 

 prey and their enemies, if they had any, their brains did not 

 keep pace with their brawn. Thespesius, who was twenty-five 

 feet long and a dozen high, had a brain weighing less than a 

 pound, while Triceratops, who probably tipped the scales at 

 something over two tons, did not possess over two pounds of 

 gray matter. Some indeed had more nerve in their hind quar- 



BRONTOSAURUS, THE "THUNDER-LIZARD " 



Prom a restoration by Chas. B. Knight. 



Courtesy of the American Museum of Natural History. 



ters than in their head ; in Stegosaurus, the sacral enlargement 

 of the spinal cord, which controlled the powerful hind legs, 

 being twenty times as large as the brain. Corresponding 

 with their paucity in brain substance the intelligence of 

 these creatures must have been low indeed, and this, together 

 with the vast bulk of many of them, may have contributed 

 to their extinction. 



But the dinosaurs were not the only members of the reptile 

 tribe which dominated the world in Mesozoic days. There 

 were reptilian aeroplanes and submarines as well. In the 

 great Cretaceous sea which divided North America into 

 eastern and western continents, covering the fertile plains and 



