FOSSIL BIRDS 



537 



While in former times existing birds were divided into a 

 Jarge number of " orders," tliese are now known to be sub- 

 divisions of the two sub-classes Ratitm and Carinatm, and 

 probably in many cases should be honored only with the rank 

 ■of sub-orders. The discovery of the Archwopferyx and of 

 birds with teeth and biconcave vertebrse has essentially mod- 

 ified prevailing views as to the classification of birds. 



Sub-class 1. Saururm. — The oldest bird, geologically 

 speaking, is the Archwopteryx (Fig. 460) of the Jurassic 

 slates of Solenhofen, Germany. This was a bird about the 

 «ize of a crow, the tail being 23 cent. (8-9 inches) long, but 

 longer than the body, supported by many movable vertebrse 



Fig. J60.— EestoratJon of ArcJueopteryx macrura.— After Owen, from Nicholson. 



and covered with feathers in distichous series, not in the 

 shape of a fan. The jaw-bones were long, and contained 

 conical teeth. The head, shoulder girdle, and fore limbs, 

 with their three digits, were reptilian in form. (Vogt.) In 

 these respects and in the long tail the creature served as a 

 ■connecting link between the reptiles, such as the bird-like 

 Compsoffnathus,a.nA the existing birds. The hind legs and 

 wings have the ordinary bird structure, though the metacar- 

 pal bones were not co-ossified; the foot consisted of three digits. 

 Sub-class 2. Odontornithes. — Still another connecting link 

 between the reptiles and birds has been discovered by Marsh 



