EVOLUTION OF BIRDS 



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shaped articular facets of the centrum seen in birds. The dorsal 

 vertebrae were not fixed and only about five went to make up the 

 sacrum. There was a long tail, with feathers arranged in parallel rows 



Fig. 308. Skulls of A, *Euparkeria; B, *Archaeopteryx; C, Culumba. 



A. angular; Al. adlachrymal ; Ar. articular; Bo. basi-occipital; C. condyle; D. dentary; 

 E. eye with sclerotic ring ; F. frontal ; J. jugal ; L. lachrymal ; Mx. maxilla ; N. nasal ; O. occi- 

 pital; Op. opisthotic; P. parietal; Pa. palatine; Pf. post-frontal; Pm. premaxilla; Po. post- 

 orbital; Pt. pterygoid; Q. quadrate; Qj. quadratojugal; S. squamosal; Sa. sur-angular; 

 Sp. splenial. (From Heilmann, The Origin of Birds, II. F. & C. Witherby, Ltd.) 



along its sides, probably an important organ, as in other animals 

 that live in trees and jump and glide. The fore-limb ended in three 

 clawed digits, with separate metacarpals and phalanges, the hallux 

 being opposable. The limb was used as a wing, for the fossils show 

 feathers on the back of the ulna and hand, but the wing area was small 

 and the shape rounded, like that of the wing of birds that fly for 



