256 



HISTORICAL PALEONTOLOGY. 



the Mesozoic seas swarmed with the huge Ichthyosaurs and 

 Plesiosaurs, and whilst the air was tenanted by the Dragon-like 

 Pterosaurs, the land-surfaces of the Secondary period were 

 peopled by numerous forms of Deinosaurs, some of them of 

 even more gigantic dimensions than their marine brethren. 

 The limbs of the Deinosaurs are, as just said, adapted for pro- 

 gression on the land; but in some cases, at any rate, the 

 hind-limbs were much longer and stronger than the fore-limbs; 

 and there seems to be no reason to doubt that many of these 

 forms possessed the power of walking, temporarily or perman- 

 ently, on their hind-legs, thus presenting a singular resemblance 

 to Birds. Some very curious and striking points connected 

 with the structure of the skeleton have also been shown to 

 connect these strange Reptiles with the true Birds ; and such 

 high authorities as Professors Huxley and Cope are of opinion 

 that the Deinosaurs are distinctly related to this class, being in 

 some respects intermediate between the proper Reptiles and 

 the great wingless Birds, like the Ostrich and Cassowary. On 

 the other hand, Professor Owen has shown that the Deinosaurs 

 possess some weighty points of relationship with the so-called 



Fig. 180. Skull of Megalosaurus, on a scale one-tenth of nature. Restored. 

 (After Professor Phillips.) 



" Pachydermatous " Quadrupeds, such as the Rhinoceros and 

 Hippopotamus. The most important Jurassic genera of 

 Deinosauria are Megalosaurus and Cetiosaurus, both of which 

 extend their range into the Cretaceous period, in which 

 flourished, as we shall see, some other well-known members 

 of this order. 



