560 HISTORICAL GEOLOGY 



that, notwithstanding its large size, it was so lightly built that in life 

 it did not weigh more than 25 pounds. In fact, the bones of the 

 largest specimen, even as petrified, do not weigh more than 5 or 6 

 pounds. When not sailing in the air, pteranodons probably spent 

 their time suspended from clifFs or trees by their slender, clawed fingers. 

 Pteranodons lived upon fish, as is shown by the fishbones and scales 

 found within their skeletons. Because of the small pelvis, we must 

 suppose that if they laid eggs, the eggs were very small. 



Because of the high degree of specialization of the earliest ptero- 

 saurs, nothing definite can be said as to their ancestry, but it is possi- 

 ble that pterosaurs, carnivorous dinosaurs, and birds all sprang from 

 a common ancestor (such as Euparkeia). (Broom.) Although flying 

 animals they were not the ancestors of birds. The first evidence of 

 their appearance has been found in the later Triassic, but they did not 

 reach North America until after the middle of the Jurassic, at which 

 time they swarmed over the epicontinental seas. None lived into the 

 Upper Cretaceous. 



REFERENCES FOR PTEROSAURS 



Chamberlin and Salisbury, — Geology, Vol. 3, especially pp. 101 and 179. 

 Eaton, G. F., — Pteranodon: Am. Jour. Sci., Vol. 17, 1904, pp. 318-320. 

 Hutchinson, H. N., — Extinct Monsters and Creatures of Other Days, pp. 199-210. 

 Lucas, F. A., — Animals before Man, pp. 209-219. 

 Lucas, F. A., — The Greatest Flying Creature, etc.: Smithsonian Inst. Rept., 1901, 



pp. 654-659. 

 Seeley, H. G., — Dragons of the Air. 



Williston, S. W., — Winged Reptiles: Pop. Sci. Monthly, Vol. 60, 1902, pp. 314-322. 

 Williston, S. W., — The Wing Finger of Pterodactyls: Jour. Geol., Vol. 19, 191 1, 



pp. 696-705. 

 Woodward, A. S., — Vertebrate Paleontology. 

 Zittel-Eastman, — Textbook of Paleontology. 



Toothed Birds 



Archaeopteryx. — If the skeletons of the earliest known bird had not 

 had featrTenfassociated with them, it is probable that they would have 

 been described as belonging to the Reptilia, with some birdlike char- 

 acters. This oldest bird (Archaeopteryx; Greek, archaios, old, and 

 pteruxy a wing) (Fig. 521) was about the size of a small crow, with a 

 small, stout, birdlike head and a birdlike brain, but its jaws, instead 

 of being of horn as in modern birds, were provided with sharp, conical 

 teeth. The wing was peculiar in having three reptile-like claws, 

 by means of which the bird could crawl about the trees, instead of 



