MU SO ZOIC ERA. AGE OF REPTILES. 335 



reptiles in fact, the liugest animals which have ever 

 walked the earth were of this order. They were also 

 the most highly organized of reptiles ; for, if the marine 

 saurians connected this class with fishes, the dinosaurs 



FIG. a82. Jurassic reptiles Ichthyosaurus and Plesiosaurus : chthyosaurus com- 

 munis, x T ^. 



connected it with the higher class of birds. Some of the 

 characters connecting them with birds are the following: 

 1. Many of them had long, powerful hind-legs, large hip^ 

 bones, and strong sacrum, and very short and small fore- 



FIG. 283. Jurassic reptiles Ichthyosaurus and Plesiosaurus : Plesiosaurus doli- 

 chodeirus, restored, x F V 



legs. These characters show that they walked mainly on 

 their hind-legs, in the manner of birds. 2. Many of them, 

 like some birds, had only three toes on the hind-feet, so 

 that they made tracks which were bird-like. 3. There 

 were peculiarities about their ankle-joints which were 

 still more bird-like. 



