690 BIRDS. 



Pedigree. Birds have many structural affinities with 

 Reptiles; some of the ancient Dinosaurs present approxi- 

 mations to Birds ; the extinct flying Pterodactyls show that 

 it was possible for flight to be developed among Reptiles ; 

 the oldest bird Archczopteryx is in many ways a 

 'connecting link between the two classes; and the develop- 

 ment of some Birds reveals many remarkable resemblances 

 with that of Reptiles, therefore, with the strength of the 

 general argument for evolution to corroborate us, we 

 conclude that Birds evolved from a Reptile stock. This 

 stock was in all probability the order of bipedal Dinosaurs 

 known as Ornithischia. 



It is likely, then, that Birds arose from an ancient Saurian 

 stock, but by what steps and under what impulses we do 

 not know. To some it seems enough to say that the 

 evolution was accomplished gradually in the course of 

 natural selection by the fostering of fit variations and the 

 elimination of the disadvantageous ; -to others it seems that 

 the incipient birds were "fevered representatives of reptiles, 

 progressing in the direction of greater and greater con- 

 stitutional activity " ; but both these suggestions leave 

 much in the dark, leave us still to "wonder how the 

 slow, cold-blooded, scaly beast ever became transformed 

 into the quick, hot-blooded, feathered bird, the joy o/ 

 creation" 



