A DEFINITION OF EVOLUTION 



,1st dorsal vertebra 



-Cleiltirum 



Lost presacrol vertebra (no, 27) 

 /f/rj j.^Sacra\ vertebrae 



Figure 11. Skeleton of a Primitive Reptile, Haptodus. (From Ronier, "The Ver- 

 tel)rate Body," 2nd Ed., W. B. Saunders Co., Philadelphia, Pa., 1955.) 



Nasal 

 Incisive 



Lachrymal 



;^ Phalanges 



Carpo • metacarpus 



■Carpus 

 V Ulna 



Clavicle — ^\\ y 

 Coracoid'' 



Pygostyle 



Tarso - metatarsoA 



Figure 12. Skeleton of a Bird. ( After Bradley. ) 



34 



