REPTILES IN GEOLOGY 



155 



were so birdlike in appearance they show by their 

 structure that they are not the ancestors of our birds, 



Fig. 75. — Finback lizard floating on the surface of the water, borne 

 along by the wind. 



but were just a thrust of soft material into the 

 birdward direction. In some way they were not 

 fitted to survive, and with the rest of the freaky ex- 

 periments of Nature they died out. We can scarcely 

 guess at the cause of their disappearance. Perhaps 

 their immense size finally made them too cumber- 

 some to procure food easily, especially if the climatei 

 changed in their region — and those were changing 

 days. 



Their extermination by the more active mammals 

 which followed them seems hardly probable, since so 

 many of the reptiles were aquatic and so few, if any, 



