454 



THE TRIASSIC PERIOD 



rare forms. The Triassic reptiles are much more common and 

 better preserved in Europe than in America, only two orders 

 having as yet been found here ; but such American genera as do 

 occur show that there was no essential difference between the 

 reptilian faunas of the two continents. 



The Rhynchocephalia, which are very near to the Permian 

 Proganosauria, are represented by Telerpeton and Hyperodapedon. 

 Allied to the Crocodiles are the little Aetosaiwus and the formi- 

 dable Belodon (Fig. 150), the latter found also in this country. 

 The first of the dolphin-like Ichthyosaurs, which become so 

 important in the Jurassic, are sparingly found in the Trias. 

 Another group of sea-dragons, the P/esiosaurs, which attain such 



FIG. 150. — Skull of Belodon Kapffii, about -^ natural size. (Zittel.) 



great development in Jurassic times, is represented in the Trias 

 by small ancestral forms, Nothosaurus, etc. These are of extraor- 

 dinary interest, as showing the descent of the purely marine Ple- 

 siosaurs, with their swimming paddles, from terrestrial reptiles 

 which had feet adapted for walking. 



One of the most characteristic of the Mesozoic orders of rep- 

 tiles is that of the Dinosauria, of which the Trias has many 

 representatives ; but clearly there were very many more than 

 have yet been found, for the Newark sandstones of the eastern 

 United States have preserved a great variety of Dinosaurian foot- 

 prints, but very few bones have been found in these rocks. The 

 Dinosauria were a much diversified order of reptiles, adapted for 

 very different habits of life : some were herbivorous, others car- 

 nivorous ; some walked on all fours ; others were occasionally or 

 habitually bipedal, and walked upright after the manner of birds, 

 with which they have many structural features in common. The 



