VERTEBRATE LIFE IN AMERICA. 525 



The first appearance of birds in America, according to our present 

 knowledge, was during the Cretaceous Period, although many an- 

 nouncements have been made of their existence in preceding epochs. 

 The evidence of their presence in the Trias, based on footprints and 

 other impressions, is, at present, as we have seen, without value ; 

 although we may confidently await their discovery there, if not in 

 older formations. Archmopteryx, from the European Jura, the oldest 

 bird known, and now fortunately represented by more than a single 

 specimen, clearly indicates a much higher antiquity for the class. 

 The earliest American forms at present known are the Odontornithes, 

 or birds with teeth, which have been exhumed, within the last few 

 years, from the chalk of Kansas. The two genera Hesperornis and 

 Ichthyomis are types of distinct orders, and differ from each other 

 and from Archozopteryx much more than do any existing birds among 

 themselves; thus showing that Birds are now a closed type, and that 

 the key to the history of the class must be sought for in the distant past. 



In Hesperornis, we have a large aquatic bird, nearly six feet in 

 length, with a strange combination of characters. The jaws are pro- 

 vided with teeth, set in grooves; the wings were rudimentary 

 and useless ; while the legs were very similar to those of modern 

 diving birds. This last feature was merely an adaptation, as the 

 more important characters are struthious, showing that Hesperornis 

 was essentially a carnivorous swimming ostrich. Ichthyomis, a small 

 flying bird, was stranger still, as the teeth were in sockets, and the 

 vertebrse biconcave, as in fishes and a few reptiles. Apatomis and 

 other allied forms occur in the same beds, and probably all were pro- 

 vided with teeth. It is strange that the companions of these ancient 

 toothed birds should have been Pterodactyls without teeth. In the 

 later Cretaceous beds of the Atlantic coast various remains of aquatic 

 birds have been found, but all are apparently distinct from those of 

 the West. The known genera of American Cretaceous birds are 

 Apatornis, JBaptomis, Graculavus, Hesperornis, Ichthyomis, laomis, 

 Lestornis, Palceotringa, and Telmatomis. These are represented by 

 some twenty species. In Europe, but two species of Cretaceous birds 

 are known, and both are based upon fragmentary specimens. 



During the Tertiary period, birds were numerous in this country, 

 and all yet discovered appear to have belonged to modern types. 

 The Eocene species described are mostly wading birds, but here, and 

 in the later Tertiary deposits, some characteristic American forms 

 make their appearance, strongly foreshadowing our present avian 

 fauna. The extinct genera are the Eocene Uintomis, related to the 

 woodpeckers, and Aletornis, which includes several species of waders. 

 Among the existing genera found in our Tertiary beds are Aquila, 

 Bubo, Meleagris, Grus, Graculus, Puffinus, and Catarractes. The 

 great auk (Alca impennis), which was once very abundant on our 

 northeast coast, has become extinct within a few years. 



