50 THE STRUCTURE AND LIFE OF BIRDS chap. 



(i) The head of a pterodactyl is put on at right 

 angles to its neck like a bird's. The head in most 

 reptiles continues the line of the neck. 



(2) The sternum or breastbone is broad and has 

 a crest in the middle. This is just what might be 

 expected where great strength is required in the 

 fore limbs and the parts connected. The mole also 

 shows a great development of breastbone : for bur- 

 rowing this is as necessary as it is for flight. 



(3) The scapula is thin and blade-like, and the 

 angle it makes with the coracoid is less than a right 

 angle. 



(4) The ilium, the bone of the pelvis that unites 

 with the backbone, is produced both ways, in front 

 of and behind the thigh-joint. This is eminently 

 characteristic of birds. 



Altogether the pterodactyl is so near to being a 

 bird that we must, before leaving the subject, briefly 

 show why he is after all a reptile. (1) The hand has 

 at least four fingers, all but the last of these bear- 

 ing claws ; (2) there are no feathers ; (3) the ischium 

 and pubis are at right angles to the ilium, instead of 

 running parallel as in birds ; (4) the pelvis is weak, 

 so that it is extremely unlikely that he could walk 

 upright. In spite of their presumable intelligence and 

 high temperature, in spite of their power of flight, 

 pterodactyls were still reptiles. Many species of them, 

 some not larger than sparrows, others with a span 

 of twenty-five feet from wing tip to wing tip, lived and 

 throve when reptiles were the dominant class upon 

 the earth, and, no doubt, they preyed upon lizards, 

 birds, and mammals. 



