Sauropsida : Class Aves 



=5S 



539 



Fig. 417. Fossilized bones and feathers of Archueopleryx, as they appear on a 

 slab of limestone. Above the slab is shown a partial reconstruction of the distal 

 part of the wing, and below is represented the foot. (Courtesy, Zittel: "Handbuch 

 der Palaeontologie," Munich. R. Oldenbourg. ) 



and tapered gradually to the tip of the tail as in a lizard — there was no 

 terminal pygostyle. So far as can be ascertained, the vertebrae were 

 amphicoelous (as in Sphenodon) . The ribs lack uncinate processes, but 

 the animal may have had cartilaginous uncinates which did not fos- 

 silize. The sternum, very poorly preserved, was probably small and 

 without a carina. Abdominal ribs (gastralia) were present (as in 

 Sphenodon and Crocodilia). The skeleton of the limbs is more reptilian 

 than avian, especially that of the forelimb, which has three strongly 

 developed digits, each terminating in a long, pointed claw. The three 

 metacarpals are not fused to one another nor to the carpals — that is, 

 there is no carpo-metacarpus as in modern birds. The skeletons show 

 no signs of pneumaticity of bones. 



These two skeletons so closely resemble numerous fossil reptilian 

 skeletons (being especially similar to those of certain small dinosaurs) 

 that they would not arouse great interest but for the fact that the 

 fossils not only prove the existence of feathers but to a large extent 

 show the relations of the feathers to regions of the body. The feathers 

 were large and, apparently, structurally similar to the quill-feathers 

 of modern birds. The fossils clearly show well-developed primary and 

 secondary remiges attached to the hand and forearm respectively, as in 

 modern birds. The long tail carried numerous rectrices arranged in a 

 single row along each side of it. They were symmetrically placed, 

 possibly each vertebra supporting a pair. Their axes sloped sharply 



