PTEROSAURIA. 



389 



sternum has a keel and there is no clavicle. The skull is rounded and 

 bird-like. The occipital condyle is single and on the base of the skull. 

 Tha cranial bones ankylose early as in birds, the orbits are large and with 



FIG. 215. Dimorphodon macronyx restoration x |, L. Lias (after Owen, from Woodward) 

 a antorbital fossa ; n external nares ; o orbit. 



sclerotic plates, and there is a wide antorbital fossa as in Aves and Dino- 

 sauria. There is a postf rental, and both upper and lower temporal arcades 

 are present. Teeth are frequently present (on the margins of the jaws only), 



