iv CONNECTING LINKS 



47 



His teeth, as I have explained above, do not separate 

 him from the bird. In fact, it is far more a bird's 

 head than a reptile's. Proceeding now to the long 

 bones we find that many of them have a very 

 remarkable feature ; they have undoubted air cavities. 

 These two points — the birdlike character of the skull, 

 and the aeration of the bones — are, I think, the most 

 important of all. When they are combined with power 

 of flight we can infer from them other characters of 



Fig. 18.— Pterodactyl, Rhamphorhyncus phyllurus restored (after Marsh). 



which no direct evidence is obtainable, and principally 

 this — the pterodactyl must have been a warm-blooded 

 animal. Flight requires great vigour such as is not 

 found in any cold-blooded creature. Flying-fish can 

 hardly be said to fly, nor can the so-called Flying 

 Dragon. Its wings are merely parachutes. Moreover 

 no animal that we know of combines a highly-developed 

 brain with cold blood. Among existing animals, birds, 

 who on the average have a decidedly higher tem- 

 perature than mammals, have, very many of them, 

 pneumatic bones. It is true that the same tendency 

 to pneumaticity is found in the bones of the Dinosaurs 



