126 EXTINCT MONSTERS 



birds are descended from Dinosaurian ancestors; while others, 

 with Professor Owen, consider the resemblance accidental, and in 

 no way implying relationship. Huxley has proposed the name 

 Ornithoscelida, or bird-legged, for these remarkable reptiles. 



Dinosaurs must have formerly inhabited a large part of the 

 primaeval world ; for their remains are found, not only in Europe, 

 but in Africa, India, North and South America, and even in 

 Australia ; and the geologist finds that they reigned supreme on 

 the earth throughout the whole of the great Mesozoic era. Their 

 bodies were, in some cases, defended by a formidable coat of 

 armour, consisting of bony plates and spines, as illustrated by 

 the case of Polacanthus (p. 173), thus giving them a decidedly 

 dragon-like appearance. The vertebrae, or bony segments of the 

 back-bone, generally have their centra hollow on both ends, as 

 in the Ichthyosaurus; but in the neck and tail they are not 

 unfrequently hollow on one side and convex on the other. In 

 some of the largest forms the vertebrse are excavated into hollow 

 chambers. This is apparently for the sake of lightness; for a 

 very large animal with heavy solid bones would find it difficult 

 to move freely. In this way strength was combined with 

 lightness. 



All the Dinosaurs had four limbs, and in many cases the hind 

 pair were very large compared to the fore limbs. They varied 

 enormously in size, as well as in appearance. Thus certain of 

 the smaller families were only two feet long and lightly built; 

 while others were truly colossal in size, far out-rivalling our 

 modern rhinoceroses and elephants. 



The limbs of Cetiosaurus, for example, or of Stegosaurus, 

 remind us strikingly of those of elephants. The celebrated Von 

 Meyer was so struck with this likeness that he proposed the name 

 Pachypoda for them, which means thick-footed. Professor Owen 



