FLYING DRAGONS, OR PTERODACTYLES 



2397 



the sides of the body to include the upper portions of the legs, between which it was 

 extended to embrace the base of the tail in those forms in which the latter append- 

 age was fully developed. More- 

 over, in the long-tailed species, 

 the extremity of the tail itself 

 was provided with a racket- 

 shaped expansion of membrane, 

 which may have served the pur- 

 pose of a rudder in flight. If it 

 be asked how the presence of 

 such membranes is known, it 

 may be answered that in many 

 of the specimens of these rep- 

 tiles entombed in the fine- 

 grained lithographic limestones 

 of Bavaria the actual impressions 

 of these membranes have been 

 preserved. The elongated fifth 

 finger of the wing had no claw 

 at the extremity, although the 

 three middle fingers were thus 

 provided. With regard to the 

 first finger, or the one corre- 

 sponding to the human thumb, 

 this may have been represented 

 by the small splint-like bone 

 seen depending from the wrist 

 in the figured skeleton. The 

 hind-limbs present no special 

 peculiarities, but, as most of the 



bones of the skeleton were hollow and permeated by air, like those of birds, we may 

 infer that the lungs were probably also constructed after the avian fashion. The 

 vertebrae of the neck resembled those of living crocodiles in having a ball at the 

 hinder end of the body and a cup in front. In general conformation the skull was 

 remarkably bird-like, the snout being produced into a beak, which in some cases 

 was provided with teeth, while in others, as shown in the figure on p. 2362, it 

 was toothless, and probably insheathed during life with horn. Bird-like features 

 are likewise shown by the large size of the brain case, of which the component 

 bones were fused together, and also by the union of the extremities of the two 

 branches of the lower jaw. 



Pterodactyles flourished during the greater part of the Secondary period, dating 

 from the epoch of the Lias, and continuing to the close of the one during which the 

 Chalk was deposited. They are represented by several well-marked types, which 

 may be arranged under three family groups. Of these the most specialized forms are 

 the toothless pterodactyles or pteranodonts, from the Cretaceous rocks of North 



SKELETON OF PTERODACTYI.E. 



The creature is lying on its back, with the head bent to the left 

 side. a. indicates the left pubic bone; the haunch bone or ilium 

 being shown on the opposite side. 



