226 THE HISTORY OF CREATION. 
These colossal reptiles, which attained a length of more than 
fifty feet, are the largest inhabitants of the land which have 
ever existed on our globe; they lived exclusively in the 
secondary epoch. Most of their remains are found in the 
lower cretaceous system, more especially in the Wealden 
formations of England. The majority of them were fearful 
beasts of prey (the Megalosaurus from twenty to thirty, 
the Pelorosaurus from forty to fifty feet in length). The 
Iguanodon, however, and some others lived on vegetable 
food, and probably played a part in the forests of the chalk 
period similar to that of the unwieldy but smaller elephants, 
hippopotami, and rhinoceroses of the present day. 
The Beaked Reptiles (Anomodontia), likewise also long 
since extinct, but of which very many remarkable remains 
are found in the Trias and Jura, were perhaps closely related 
to the Dragons. Their jaws, like those of most Flying 
Reptiles and Tortoises, had become changed into a beak, 
which either possessed only degenerated rudimentary teeth, 
or no teeth at all. In this order, if not in the preceding one, 
we must look forthe primary parents of the bird class, which 
we may call Bird Reptiles (Tocornithes). Probably very 
closely related to them was the curious, kangaroo-like 
Compsognathus from the Jura, which in very important 
characteristics already shows an approximation to the 
structure of birds. 
The class of Birds (Aves), as already remarked, is so 
closely allied to Reptiles in internal structure and by 
embryonal development, that they undoubtedly originated 
out of a branch of this class. Even a glance at Plates II. 
and III. will show that the embryos of birds at a time 
when they already essentially differ from the embryos of 
