242 THE HAUNTS OF LIFE 



were adepts, since the breastbone has only a 

 slight keel for the fixing on of the wing- 

 muscles ; and we know that in birds a 

 prominent keel is associated with highly 

 developed flying power, whereas the running 

 birds like the ostrich have no keel at all. On 

 the other hand, the Flying Dragons show, as 

 flying birds do, a solidifying of the middle 

 part of the backbone, giving the wings a firm 

 fulcrum against which to work. It is probably 

 quite safe to say that the Pterodactyls represent 

 a " lost race " ; they certainly were not the 

 ancestors of birds. It may be, however, that 

 the ancestors of the Pterodactyls and the 

 ancestors of our birds were related to one 

 another. 



THE FLIGHT OF BIRDS 



The third solution was a triumphant one : it 

 gave birds their mastery of the air. There 

 seems no doubt that birds sprang from an 

 extinct stock of Dinosaur reptiles which had 

 become bipeds ; and it is highly probable that 

 they were to begin with swift runners that 

 flapped their scaly fore-limbs and took long, 

 skimming leaps along the ground. When 



