MEDIEVAL OR MESOZOIC TIMES. 195 



has shown that the American pterosaurs were toothless, differing 

 in that respect from the European, and for this reason erects them 

 into a new order, called Pteronodontia, which means winged tooth- 

 less. One of these flying saurians,' "(P. ingens), has toothless 

 jaws four feet long." Unquestionably there were many more species, 

 some gigantic, and some, as in Europe, small. They roamed through 

 the air, often plunging down to seize fish or reptile, they would fly 

 away to some rock on a neighboring coast or island and there con- 

 sume their victims at leisure. 



No crocodiles have yet been described from the Niobrara group, 

 but they were undoubtedly present in that old sea, as they existed 

 in the preceding and subsequent eras. One {Hyposaurus Webbii^ 

 Cope), obtained in the Fort Benton group of lead colored shales, 

 was about ten feet long, and belonged to the division that had sub- 

 biconcave vertebra, and with a long subcylindric snout. 



Only one species of Dinosaurs has been found in the Niobrara 

 group. They were no doubt abundant in this era, but the condi- 

 tions for their preservation were not favorable. Many have been 

 found in the geological equivalent of the Niobrara in New Jersey. 

 They were present in considerable numbers during subsequent Cre- 

 taceous eras, and no doubt on the land surfaces of the time they 

 were the rulers. 



Birds. Nothing is more remarkable about this marvelous age 

 than the peculiarities of its bird life. Like all other vertebrate 

 forms, it was almost entirely of reptilian type. Thus far eleven 

 species have^ been described from the Niobrara group deposits. 

 The New Jersey green sand has yielded five more. The Saururae 

 were the most remarkable, as they combined fish, reptile and bird 

 characters. They are embraced in two genera, Ichthyornis and 

 A-patornis. They had no horny beak, like modern birds, but in lieu 

 of it they had slender, thin and long jaws, filled with sharp conical 

 teeth in sockets, numbering at least twenty on each side below, and 

 Marsh thinks as many above, though that could not be ascertained 

 from the specimens. " Their vertebras were amphicoelous or bicon- 

 cave, as in fishes and many extinct reptiles, but in no modern bird-" 

 Marsh. Of the former there were two species, namely, Ichthyor- 

 nu dispar and /. celer. The generic name {Ichthyornis}, means fish- 

 bird, referring to the fish-like structure of its vertebrae. They had 

 a keel on the breast, like modern birds, for the attachment of the 

 muscles of flight. Marsh supposes that the tail, which was not 



