226 



THE ORIGIN AND EVOLUTION OF LIFE 



Pterosaurs 



There is no doubt that the pterosaurs, flying reptiles, were 

 adapted to fly far out to sea, for their remains are found min- 

 gled with those of the mosasaurs in deposits far from the 

 ancient shore-lines. There is no relation whatever between 

 the feathered birds and these animals, whose analogies in their 

 modes of flight are rather with the bats among the mammals. 



These flying reptiles are 

 perhaps the most extraor- 

 dinary of all extinct ani- 

 mals. While some ptero- 

 saurs were hardly larger 

 than sparrows, others sur- 

 passed all living birds in 

 the spread of the wings, 

 although inferior to many 

 birds in the bulk of the 

 body. It is believed that 

 they depended almost entirely upon soaring for progression. 

 The head in the largest types of the family {Pteranodon) is 

 converted into a great vertical fin, used, no doubt, in directing 

 flight, with a long, backwardly projecting bony crest which 

 served in the balancing of the elongate and compressed bill. 

 The feeble development of the muscles of flight in these an- 

 cient forms is compensated for by the extreme lightness of the 

 body and the hollowness of the bones. 



Origin of Birds 



It is believed that in late Permian or early Triassic time a 

 small lizard-like reptile of partly bipedal habit and remotely 

 related to the bipedal ancestors of the dinosaurs passed from 



Fig. 103. Restoration of the Pterodactyl, 

 Showing the Soaring Flight. 



After the Aeronautical Journal. London. 



