DIXOSAURIA 491 



interior sea. These were gigantic, carnivorous marine lizards, 

 with the limbs converted into swimming paddles (see Fig. 162). 

 Turtles, both fresh-water and marine, abound, and some were very- 

 large. Lizards and Snakes are but scantily represented, not dis- 

 playing the manifold variety of structure which they afterwards 

 acquired. Crocodiles, like those of modern days, were ubiquitous 

 in both fresh and salt waters. 



The Pterosaurs of the Cretaceous are remarkable for their 

 great size, far exceeding that of the Jurassic species. Ornitho- 

 stonia, which has been found both in Kansas and in Europe, had a 

 head of nearly 3 feet in length, with a long, pointed, toothless 

 bill, like that of a bird ; the spread of wings exceeded 20 feet. 



The Dinosaurs continue in even greater profusion than in the 

 Jurassic ; they are, of course, much commoner and better pre- 

 served in fresh-water deposits than in marine, and hence are best 

 known from the base and the summit of the system. Many of the 

 genera were the largest land animals that ever lived, and the size 

 of the bones is astonishing. Ornithopsis, Diplodocus, and Cetio- 

 saurus are examples of immense, quadrupedal herbivorous Dino- 

 saurs. In Stegosau?-us the shortness of the fore limbs gives the 

 back a very strong curvature ; this remarkable genus had a defen- 

 sive armour of enormous bony plates and spines, extending in the 

 middle line of the back from the head to the end of the tail. 

 Camptosaurus was also herbivorous, but had an erect bipedal 

 gait. Megalosaui'us was a carnivorous reptile, with huge teeth 

 and a nasal horn ; its fore legs are very small and its gait was 

 erect. These genera and others are all found in the Como beds 

 (which may be Jurassic), and very similar ones occur in the 

 Trinity and lower part of the Potomac, as also in the Wealden of 

 Europe. Especially famous is the genus Iguanodon, of which 

 many complete skeletons have been found in Belgium. Dino- 

 saurs are much less common in the marine Upper Cretaceous, but 

 the green sands of New Jersey have yielded Hadrosaurus, an 

 herbivorous Dinosaur much like Iguanodon, and some carnivorous 

 types also. The Laramie and Denver beds have preserved many 

 fine specimens, which show that the Dinosaurs flourished in almost 



