278 



VERTEBRATE ZOOLOGY 



4. The centra of the neck and back vertebrae were biconcave, as 



in many primitive reptiles. 



5. The fibula and tibia were not coalesced. 



6. The tail was long and lizard-like, composed of about 21 free 



post-sacral vertebrae (Fig. 148, A). At least the first 12 ver- 

 tebrae bore paired flight feathers with well-defined shafts. 



7. There were structures that have been interpreted as abdominal 



ribs. 

 Two additional characters that are not reptilian nor fully avian 

 should be mentioned. 



Fig. 150. — Skull of Archmoplerijx, showing teeth and sclerotic plates. (From 

 Headley, after Dames.) 



1. The leg was rather weak as compared with that of most modern 



birds, a fact that militates against the theory of the cursorial 

 origin of flight. The pelvic girdle is much smaller than in 

 birds of the present, and is not fused with the sacral 

 vertebrae. 



2. The feathers of the wing ^^■ere entirely typical both in form and 



in arrangement, Init were rather small for the size of the body. 

 The general contour feathers wei'c (n'ideutly less abundant 

 than in a modern full-fledged bird. A theoretical reconstruc- 

 tion of the plumage is shown in Fig. 148, I. 



Modern Birds (Neornithes) 



On account of the fact that Archccopteryx differs fundamentally 

 from all other birds both living and extinct, it is placed in a separate 



