REPTILES IN GEOLOGY 



155 



were so birdlike in appearance tliej show by their 

 structure that thev are not the ancestors of our bird^. 



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



along by the wind. 



but were just a thrust of soft material into the 

 birdward direction. In some wav thev were not 

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

 periments of Xature they died out. We can scarcely 

 guess at the cause of their disappearance. Perhaps 

 their immense size finallv made them too cumber- 

 some to procure food easily, especially if the climate 

 changed in their region — and those were changing 

 days. 



Their extermination bv the more active mammals 

 which followed them seems hardly probable, since so 

 many of the reptiles were ac^uatic and so few, if any, 



