43 O DINOSAURIA 



Order IV. CERATOPSIA. 



Pubic bones simple, forming a symphysis, post-pubic branches being 

 absent. The mandible carries a toothless " pre-dental," and the 

 fused premaxillaries carry a similar, toothless, " rostral " bone. 



The teeth of the upper and lower jaws are alveolar, and 

 have two roots. The fore-limbs are little shorter than the hind- 

 limbs ; pentadactyle and plantigrade, with broad hoofs. Femur 

 without a fourth trochanter. Limb-bones solid. The skull is 

 large, and remarkable for a pair of long frontal bony cores, which 

 probably carried large, pointed horns ; the parietal bones form a 

 huge, horizontally broadened out crest, which extends backwards 



FIG. 102. Skeleton of Triceratops prorsus. x 7^. (After Marsh.) 



over the neck. Upon this cranial neck-shield follow small 

 dermal bony plates. These miraculous creatures flourished during 

 the Cretaceous epoch in Europe and in North America. Some, 

 for instance, the American Triceratops Jlabellatus, reached a huge 

 size, its skull alone measuring more than 5 feet in length, 

 while that of T. prorsus is, including the neck-shield, about 7 

 feet long. The total length of this monster, the back of which 

 stands about 8 feet high, is more than 20 feet. Other genera 

 seem to have a well-developed dermal armour, e.g. Nodosaurus 

 of the Middle Cretaceous period of Wyoming. 



The Ceratopsia combine characters of the Sauropoda and of 

 the Stegosaurian Orthopoda ; in their pelvis they agree with the 

 former, in the development of dermal armour and a predental 

 bone they agree with the latter, while they differ from either by 

 the possession of a rostral element. 



