THE CRETACEOUS PERIOD 



267 



thought will, when mounted, show a length of over 100 feet. It 

 has been estimated that one of these large brutes must have 

 weighed about 40 tons. Note the extremely long neck and tail, 

 very small head, and strong bones of the four great legs. Thigh 

 bones 7 feet long are known. They were five-toed and plantigrade, 

 and doubtless walked with body well above ground (Fig. 168). 



Fig. 167 

 A Mosasaur, Tylosaurus dyspelor, of the Enaliosaur division of Mesozoic 

 Reptiles. Maximum length about 75 feet. Restoration by C. R. Knight 

 under the direction of H. F. Osborn. (Courtesy of the American Museum 

 of Natural History, from Scott's "Geology," by permission of The 

 Macmillan Company.) 



All were plant-eaters and provided with grinding teeth. Sauropods 

 ranged through all the Mesozoic except the Triassic. 



The Stegosaurs are so named because of the double row of great 

 bony plates on the back of each of these most remarkable brutes 

 (Fig. 169) which attained a maximum length of 30 to 40 feet. The 

 long, powerful tail had several pairs of long spines toward the end 

 instead of plates. As compared with the Sauropods the neck was 

 short. They were quadrupedal, four-toed in front, and three-toed 



