KEPTILIA. 45 



The order is limited to the Jura and Cretaceous. Six species 

 have been found in the Cretaceous chalk of Kansas, all toothless, 

 probably with horny beaks, and forming a group so distinct from 

 the Old World forms that Professor Marsh places them in a sep- 

 aiate order — Pteranodontia. 



One species of Pterodactyl, Devmodacfylus montanns, Marsh, 

 has been found in the Upper Jurassic of Wyoming. 



Some authors have regarded the Pterodactyls as the progenitors 

 of the birds. Others have thought them to be the ancestors of 

 the ilying birds (Carintse), and only the struthious birds (Katitaj), 

 to be descended from the Dinosaurs. 'Professor Marsh holds 

 that the Pterodactyls were not in the avian line of descent. He 

 writes as follows concerning the relationship of the genera: 

 '' The oldest European form, Dimor2)hodon , from the Lower Lias, 

 had the entire jaws armed with teeth, and was provided with a 

 long tail. The later genus, Pterodaetylus^ retained the teeth, 

 but had essentially lost the tail ; while Bhamjjhorhynchus had 

 retained the elongated tail, but had lost the teeth from the fore 

 part of the jaws. In the genus Pteranodon., from the American 

 Cretaceous, the teeth are entirely absent, and the tail is a mere 

 rudiment. In the gradual loss of the teeth and tail these reptiles 

 followed the same path as birds, and might thus seem to approach 

 them, as many have supposed. This resemblance, however, is 

 only a superficial one, as a study of the more impoi'tant characters 

 of the Pterodactyls shows that tliey are an aberrant type of rep- 

 tiles, totally off the line through which the birds were developed." 



The European forms are mostly of small size, the expanse of 

 wing measuring from three feet down to the size of a sparrow. 

 The Pteranodons are mostly gigantic, some of them being esti- 

 mated to have an expanse of nearly twenty -five feet. 



No. 65. [241] Pterodactylus crassirostris, Goldfuss. 



Skeleton, on slab (cast). The Pterodactyl was one of the most extraor- 

 dinary of all the reptiles yet discovered, and its strange combination of char- 

 acters has been the cause of much difference of opinion regarding its true 

 nature. Collini, in 1784, was the first to investigate the characters of this 

 strange animal; he considered it a fish. Blumenbach decided it was a bird; 

 Sommering, a mammal, Spix, that it was intermediate between monkeys and 

 bats; Macleay, a link between mammals and birds; and Agassiz thought it a 

 strictly marine reptile. Cuvier, in 1800, determined the place and name it 

 now holds. 



