THE AFFINITIES OF BIRDS Io7 



their hinder feet, and that, as the Ornithoscelida did the same, 

 the resemblance of structure arises from a resemblance of 

 function. But I doubt if the majority of the Dinosauria 

 stood more habitually upon their hind limbs than kangaroos 

 or jerboas do ; and, unless there was some genetic connection 

 between the t\vo, I see no reason why the hind limbs of 

 Ornithoscelida should resemble those of birds more than they 

 resemble those of kangaroos.' In addition to this it may be 

 pointed out that Hallopus, which appears to have been very 

 probably a leaping dinosaur, has not the specially ornithic 

 form of limb ; it has large pubes and no postpubes. 



A recent description by Mr. E. T. NEWTON 1 of the skull, 

 brain cast, and cast of the auditory organ in a pterodactyle, 

 Scaphogiiathus Purdoni, shows certain most interesting 

 resemblances between the pterosaurians and birds. It is 

 possible that this pterosaurian, like Pteranodon, possessed a 

 homy beak and no teeth. But the presence or absence of a 

 beak or of teeth is no more distinctive of birds (cf. Archceo- 

 pteryx) than of reptiles. The skull shows more positive 

 points of likeness. In the first place, the bones of the 

 pterodactyle cranium are early ankylosed and well anky- 

 losed, being in this particular avian and not lacertilian. 

 The large size and backward extension of the single pre- 

 maxillary bone ( = two fused premaxillae) agree with that of 

 birds and contrasts with that of lizards. The palate shows 

 also certain interesting resemblances, more especially to 

 both emu and cassowary. As in the struthious birds and in 

 lizards also the palatines are borne off from the middle line 

 by the pterygoids ; the latter bones, moreover, as in the emu, 

 articulate at their posterior ends with both quadrate and 

 basipterygoid processes. The vomer too is birdlike in being 

 pushed backwards, owing to the extent of the premaxillse, 

 and in being thin, apparently single and bifurcate posteriorly. 

 Other general resemblances in the skeleton are the develop- 

 ment of air cavities in the bone, the large size of the orbit 

 which may, however, in the pterodactyles have had some 



1 ' On the Skull, Brain, and Auditory Organ of a New Species of Pterosaurian,' 

 Phil. Trans. 1888, B, p. 503. 



