CARNIVOROUS GROUP. 



35 



INNER AND OUTER VIEWS OF A TOOTH OF . 



(From the Quart. Joum. Geol. Soc. 



. PELOROSAUR. 



1893.) 



dinosaurs were distinguished therefrom by the circumstance that the bone known 



as the pubis (p in the figure on p. 3) enters into the composition of the cavity 



for the reception of the head of the thigh-bone. The limb -bones are solid 



throughout. From the nature of 



their teeth, which are often much 



worn by use, it may be inferred 



that these reptiles were vegetable 



feeders; and it is not improbable 



that they frequented the margins 



of lakes and rivers, where their 



inordinately long necks would 



enable them to browse with ease 



on the various aquatic plants. 



That they must have been very 



sluggish in their movements and 



stupid in their ideas is indicated 



by the wonderfully small propor- 

 tionate size of their brains. These 



dinosaurs were common both in 



Europe and the United States, the larger forms having been described under the 



names of pelorosaurs (Pelorosaurus), atlantosaurs (Atlantosaurus), brontosaurs 



(Brontosaurus), and hoplosaurs (Hoplosaurus) ; among which the atlantosaurs 



appear to have been the most gigantic. They also occur in India, Argentina, 



and Madagascar. 



Carnivorous The carnivorous dinosaurs, of which the 



Group. megalosaur (Megalosaurus) is the best known 

 example, differed from the preceding group in the form of 

 their teeth, which were compressed and sickle-shaped, with 

 sharp cutting, and frequently serrated edges. Their limb- 

 bones also were hollow ; while their vertebrae were likewise 

 hollow internally, but had no lateral cavities ; and the 

 pelvis (figured on p. 3), although of the same general 

 type as in the lizard-footed group, presented important 

 points of distinction. In place of the short feet of the 

 last-named group, the carnivorous dinosaurs had elongated 

 foot - bones, terminating in sharp claws ; the number of 

 functional toes in the hind-foot varying from four to three. 

 That they habitually walked on the toes of their hind- 

 limbs, and not (as was the case with the lizard-footed 

 group) on the whole foot, is evident from the structure of 

 this part of the skeleton, and from the circumstance that 

 the fore-limbs were considerably smaller than the hinder 

 pair, it may be inferred that progression was at least 

 frequently accomplished by the aid of the latter alone. 

 The close approximation of the huckle-bone of the ankle to 

 the lower end of the tibia foreshadows the complete 



BONES OF THE 

 FOOT OF A 

 DINOSAUR. 



RIGHT HIND- 

 CARNIVOROUS 



