THE JURASSIC PERIOD. 



249 



possess some weighty points of relationship with the so-called 

 " 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. 



Megalosaurus attained gigantic dimensions, its thigh and 

 shank bones measuring each about three feet in length, and its 

 total length, including the tail, being estimated at from forty 

 to fifty feet. As the head of the thigh-bone is set on nearly 

 at right angles with the shaft, whilst all the long bones of the 

 skeleton are hollowed out internally for the reception of the 

 marrow, there can be no doubt as to the terrestrial habits of 

 the animal. The skull (fig. 180) was of large size, four or five 



Fig. 180. Skull of Mega'ctsauriis, on a scale one-tenth of nature. Restored. 

 (After Professor Phillips.) 



feet in length, and the jaws were armed with a series of power- 

 ful pointed teeth. The teeth are conical in shape, but are 

 strongly compressed towards their summits, their lateral edges 

 being finely serrated. In their form and their saw-like edges, 

 they resemble the teeth of the " Sabre-toothed Tiger" (Machai- 

 rodns], and they render it certain that the Megalosaur was in 

 the highest degree destructive and carnivorous in its habits. 

 So far as is known, the skin was not furnished with any armour 

 of scales or bony plates ; and the fore-limbs are so dispro- 

 portionately small as compared with the hind-limbs, that this 

 huge Reptile like the equally huge Iguanodon may be 



