32 EVOLUTION 



from some ancient reptilian or saurian stock. 

 He has not ceased to wonder how this tran- 

 sition can have come about; "how the slow, 

 cold-blooded, scaly beast ever became trans- 

 formed into the quick, hot-blooded, feathered 

 bird, the joy of creation"; but he does not 

 doubt that the transition was effected. He 

 is still unwilling to make any positive state- 

 ment in regard to the precise pedigree of 

 birds, and yet he is confident that they 

 sprang from a reptilian stock. What are 

 the reasons for this confidence? 



They are threefold: (1) There are, in spite 

 of appearances, numerous structural resem- 

 blances between birds and reptiles, from the 

 scales on the feet to the composition and the 

 articulation of the lower jaw; (2) there are 

 deep similarities in development, for the 

 embryo bird and the embryo reptile travel 

 at first along parallel paths, and only grad- 

 ually part company; and (3) there are 

 extinct types which to some extent bridge 

 the conspicuous gap. A word, then, in regard 

 to these connecting links. 



One of the most treasured fossils in the 

 world of which the British Museum and 

 the Berlin Museum have each one of the 

 two known specimens is the oldest known 

 bird, Archseopteryx. These priceless skele- 

 tons were found well preserved in the lith- 



