BIRDS. 



By S. W. WILLISTON. 



Remains of birds always have been and always will be the 

 rarest of vertebrate fossils. From the habits of the great ma- 

 jority of species, together with the lightness and buoyancy of 

 their bodies in the water, it is very evident that, even where 

 they are abundant, they will not often fall into such positions 

 that they will be fossilized. Although, with our present evi- 

 dence, they first made their appearance in geological history as 

 far back as the Jurassic formation, scarcely two score of valid 

 species have thus far been discovered from the Mesozoic, and all 

 of those, with one or two exceptions, are from the Upper Creta- 

 ceous formations. 



The famous Archeopteryx, from the Jurassic of Solenhofen, the 

 earliest bird known, has long been renowned for its strange 

 mingling of reptilian and avian characters. With the wings 

 imperfectly developed, there were long reptilian fingers with 

 claws, adapted for seizing and grasping. The jaws were pro- 

 vided with well-developed teeth, and the tail was elongated as 

 in reptiles, each individual vertebra provided with a pair of 

 long feathers. 



The famous footprints of the Connecticut Triassic sandstone 

 were, for a long time, supposed to have been made by birds. 

 More recent discoveries of the remarkable reptiles known as 

 Dinosaurs have shown that it was not only possible, but very- 

 probable, that all of them were made by these animals and none 

 by birds. 



From the Lower Cretaceous no bird remains are yet known. 

 From the Upper Cretaceous, aside from the footprints noticed 

 below, the only remains yet known in America are from the 

 Green Sand of New Jersey, the Niobrara Cretaceous of Kansas, 



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