314 



ZOOLOGY 



We know of species which have become extinct within 

 recent times through the introduction of new enemies 

 among them. Such was the fate of the dodo. Then 

 remains have been preserved to us in the rocks of species 

 which lived in very remote periods. The oldest known 

 fossil bird, ArchaDopteryx, of the Jurassic age, had a long 

 tail like a lizard ; but feathers, which are only modified 

 scales, were present even in this oldest known bird. In 

 the Cretaceous rock deposits of the Great Plains there 

 have been found fossil birds with teeth set in sockets or 

 grooves, precisely as they are to-day in reptiles (Fig. 294). 

 These remains show us in the clearest manner that birds 

 have been derived from reptiles. Indeed, the two groups 

 are closely related anatomically, and are often united 

 under the name Sauropsida or lizard-like animals. 



APPENDIX TO CHAPTER XIX 



KEY TO THE ORDERS OF BIRDS 



a\. Sternum with keel for insertion of flying muscles 



[Carinatse]. 

 bi. Toes more or less webbed or fringed, legs 



used for swimming or wading. 



c\. Short legs, broadly webbed [Swimmers] Natatores 



Ct. Long legs, long, thin neck, and long beak 



[Waders] . ' . .... . . ' .. , Grallatores 



b%- Feet not webbed, fitted for walking, 

 d- With cere. 



c?i. Beak strong, and bent downward at 



point ; perching feet ; flat nail . G-allinacei 



dz. Beak not bent downward at point-; 

 short, cloven feet; nail com- 

 pressed ..... Columbinw 



