AVES. 



35 



CLASS AVES. 



Existing Birds are, perhaps, the most distinct class of animals, 

 their superficial characters being so evident and peculiar that 

 their identity is always clear, even to the most unscientific person. 

 They seem to form a "closed" group. However, their reptilian 

 aflinities are numerous and important, and the pal^eontological 

 discoveries of recent years have bridged the gap between the 

 living reptiles and birds, and leave no doubt that birds are a 

 highly specialized branch of the reptilian trunk. 



The oldest known bird is the Archceopteryx, in the Jurassic. It 

 is very reptilian, as shown by the possession of teeth, finger 

 claws, and a long series of caudal vertebrae. 



Professor Marsh has described another Jurassic bird, Laopteryx 

 priscus, from the Atlantosaur beds of Wyoming Territory. 

 It was somewhat larger than the Blue Heron, and probably had 

 teeth and biconcave vertebrae. 



The Odontornithes, of Marsh, from the Cretaceous of Kansas 

 are very remarkable birds. Ichthyoi'iiis is the type of an order 

 having teeth in distinct sockets, in long slender jaws, and with 

 vertebrae bi-concave. It was the size of a pigeon, aquatic, with 

 power of flight. The Hesperornis regalls is the only representa- 

 tive yet found of a quite different type, being wingless, aquatic, 

 and with teeth in a groove. It was six feet long. Marsh calls 

 it a " carnivorous swimming ostrich." The cretaceous beds of 

 the Atlantic coast have supplied other species of birds. Alto- 

 gether twenty species are known from American Cretaceous, and 

 two from Europe. 



All the known Jurassic birds are land birds, while all the Cre- 

 taceous ones are aquatic ; and the four oldest {Aixhceopteryx^ 

 Laopteryx, Hesperornis, Ichthy oralis), differ more widely than 

 any two existing birds. (Marsh). 



The remains of Tertiary birds are numerous, and chiefly be- 

 long to surviving groups. 



Most extraordinary additions to the palaeontology of this class 

 have been obtained from New Zealand — an island remarkable 

 for possessing but one indigenous land-mammal, and but a few 

 diminutive reptiles. Colossal birds, ranging from three to ten 

 feet in height, akin to the ostrich, but tridactyl and tetradactyl, 

 have left remains in the recent Alluvium. 



