. WINGED REPTILES. 3^7 



excelled only among insects. They were, par excellence, organisms of 

 flight, to which function all else, so far as was compatible with existence, 

 was subservient. 



It was only among the later geological forms, however, that this 

 fight specialization was carried to its extreme, a fact which has its 

 parallel in not a few other classes of animals, where it lias been only in 



Skeleton of Pteranodon (Oexithostoma). 



(lie last bitter struggles for existence that the evolution of the type has 

 been carried to its uttermost. In the accompanying figure is given a 

 restoration of Pteranodon, one of these most highly specialized ptero- 

 dactyls, based upon skeletons from the Cretaceous chalk of western Kan- 

 sas. As in all restorations of extinct animals which departed widely 

 from any now in existence, entire truthfulness of expression and 

 appearance can not be expected. A more or less close approximation to 

 the living picture is, however, assured from a complete knowledge of the 

 skeleton and the impression in the rocks of form and of membranes, 

 which have been preserved with the bones of allied forms. I use the 

 more widely known name Pteranodon for this animal, though I believe it 

 to be identical with the European genus previously called Ornithostoma. 

 The body of Pteranodon was short and relatively small; the legs 

 were slender and wealc, and loosely jointed ; the toes were small and 

 delicate, with little or no grasping power, and without claws; the tail 

 was rudimentary. As if in compensation for the greatly reduced pos- 

 terior part of the body, the whole anterior part — the head, neck, thorax 

 and anterior limbs — was extraordinarily developed. The head was slen- 

 der and elongate, with a dagger-like beak, possibly covered with a 

 horny sheath, and the jaws were wholly toothless. In the largest 

 species the head measured ov^ four feet in length, and its equilibrium 

 was maintained by a strange prolongation backward of the skull. The 

 nostrils were placed far back, and the eyes were protected by a ring of 

 bony plates, similar to those of the eyes of hawks and owls. The neck 

 was long and strong, and very flexible, with a remarkable series of 

 additional articulations unlike anything found in the neck bones 

 of other animals, whereby the thrusting and striking power of the beak 

 was greatly intensified. 



