MESOZOIC ERA. AGE OF REPTILES. 



But the Mosasaurs were the most 

 abundant and also the most character- 

 istic of all, being found only in the Cre- 

 taceous. At least fifty species are known, 

 and the remains of 1,400 are now in the 

 Peabody Museum at Yale University. 

 These were long, slender, almost snake- 

 like in form, with limbs in the form of 

 powerful paddles (Fig. 321). They were, 

 therefore, entirely marine in habits, and 

 wholly incapable of locomotion on land. 

 The head was slender, and armed with 2 

 large, recurved teeth. They were allied 

 most nearly to lizards, and therefore I 

 might be called huge sea-lizards; but, f 

 like most early animals, they were a gen- I 

 eralized type, connecting also with other g 

 orders, especially snakes. Some species a 

 were seventy to eighty feet long, and 

 had teeth seven inches in length. 



Birds. The history of the discovery 

 of fossil birds is interesting. In 1862 

 the wonderful Jurassic bird, Archceop- \ 

 teryx, already spoken of (page 338), was \ 

 discovered. But this stood alone, with- \ 

 out links connecting it with typical 

 birds. In 1870 commenced the wonder- 

 ful series of discoveries by Marsh, mostly 

 in the Cretaceous of the "West, which 

 served largely to fill up this gap. 

 About twenty species of Cretaceous birds 

 have been described by him. Of these, 

 about one half were ordinary water- 

 birds, allied to the Eails, Divers, Cor- 

 morants, etc., though of different gen- 

 era, but the other ten were wonderful 



35? 



