BIRD, FOSSIL. Fossil remains that could be referred to birds were among the later ac quisitions of paleontologists. The first were mis takenly so considered, and consisted of the famous 'bird-tracks' discovered in the 'brown stone' rocks of the Connecticut River by Hitch cock, about 1835, and extensively studied by him. These footprints may possibly. in a few instances, be traces of primitive animals properly called birds, but so far as known all are impressions made upon mud by dinosaurs and similar am phibians or reptiles of the Triassic Age. (See IJINosauRm; STEOOCEPUALIA, etc.) orq re cently true birds have been found fossil from the Jurassic Age onward, but their remains are ev erywhere comparatively scarce, due mainly to the easy destructibility of their bodies. The earliest to he identified proved to be also the earliest in time, and consisted of the remains in the Jurassic slates of Bavaria of Arehfeopteryx, whose characteristics are fully described under ARCILEOPTERYX. This seems to have been a true feather-clothed bird, with well-formed wings, but a long lizard-like tail, beset on each side with a row of horizontal quill-feathers, and a heron-like beak studded with teeth. These characteristics are so radically different from those of all other birds that the archaeopteryx is classified in a subclass of itself termed Arch;eornithes; all other birds, fossil and recent, forming another subclass, Neornithes or Euornithes. A long gap in geological time separates the period of the archaeopteryx from the next earliest fossil birds known, which belong to the upper, or more recent, part of the Cretaceous Age. These forum tions in Europe and India. but especially in the western United States, have yielded varied re mains of large birds, which. because all have teeth in the beak. have been called Odontornithes or Odontole:e. All are still of a low type of organization, showing many points of genetic affinity with reptiles, but far advanced beyond Arelecopteryx; and all were aquatic and fish eating. They approximate, indeed, so closely to the ordinary carinate birds of the present time that they are included with them in a single sub class, as above noted, of which, say Parker and Ilaswell. "they will constitute a separate series characterized by the possession of teeth and . . . that the two halves of the lower jaw remain completely separate in front, instead of having a solid bony union. Of these toothed birds the one type is known as Jehthyornis, and comprises somewhat gull-like birds characterized by having a numerous series of teeth implanted in distinct sockets, and also by the vertebra; or joints of the back articulating with one another by means of Cup-like surfaces (instead of sad dle-shaped). . . . It is quite within the bounds of possibility that these birds may be ancestral types of the modern gulls. With flesperornis (q.v.) we arc confronted with a totally different type, in which the teeth were im planted in an open groove, while the wings were rudimentary and the keel of the breast-bone was wanting, although the vertebra- resembled those of existing birds. In general organization, Hes perornis. indeed. approximated very closely to the modern divers. . . . That it was thoroughly aquatic in its habits is self-evident: while it may . . . be regarded as a specialized and flight less offshoot from the ancestral stock of the modern divers." The discovery and elucidation of these Cretaceous toothed birds was made chiefly by Prof. 0. C. Marsh, of Vale University, between 1870 and 1880, and his novelties in cluded a large number of skeletons or fragments which have been referred to various genera and are preserved in the Vale Museum at New Haven.
"They afford a most valuable contribution in favor of the doctrine of evolution, approximating more and more, as we descend in the geological scale, to reptiles, from which it may be confi dently stated the avian class has originated." With the closing of the Cretaceous Period. toothed birds seem to have disappeared, for bird-fossils from the early formation of Tertiary age lack them, and in general approach closely to modern types. Few of these fossils have been found in North America, hut Europe and South America have supplied many genera and species of various groups. increasing in numbers as we rise in the geologic scale. Among the oldest (Eocene) were certain gigantic forms, character ized by long, powerful legs and small and appar ently useless wings, but especially by "the enor mous and ponderous structure of the skull, which is quite unlike that of any recent bird,and seems out of all proportion to the limbs, gigantic as are some of the leg-bones." These have been com bined into a group (Stereornithes) including many species. chiefly of the genera Prontornis and Phororhacos, from the Miocene of Patagonia. "Brontornis, for example." according to Lucas, "had leg-bones larger than those of an ox; . . . while the great Phororhacos, one of his contemporaries, was not only nearly as large, but quite unique in build. Imagine a bird seven or eight feet in height, from the sole of his big. sharp-elawed feet to the top of his huge head. poise this head on a neck as thick as that of a horse, arm it with a beak as sharp as an ice pick and almost as formidable, and you have a fair idea of this feathered giant of the ancient pampas." The skull equaled in size that of a large horse, but whether this great equipment was used for carnivorous purposes can only be conjectured. The general affinity of these huge birds seems to be with the herons; and with them have been classed Gastornis and certain other large forms of contemporary time in Europe and North America, whose habits are supposed to be those of cursorial birds of prey. Other birds of the early Tertiary Age represented the Stega nopodes (q.v.). or were similar to gulls, penguins, cranes, kingfishers, game-birds, and many other modern types. The rocks and eaves of the Paris Basin, and of central France. and the Eocene beds of Wyoming, have been particularly fruit ful in ornitholites. The Mioeene and Pliocene eras furnish still more fossil forms, among which a large number of genera still exist, showing how early birds arrived at the perfection of their fern and adaptation. Lydekker tells us that by far the greater portion of the remains of birds from the still higher Pleistocene rocks seem to be generically if not specifically identical with those now inhabiting the district in which they occur, though their range at that time may have been different from its present extent. To this period, immediately precedent to that in which we live, belong such recently existing races as the moa, epiornis, dinornis, etc., but they are treated elsewhere.
Consult: Newton, Dictionary of Birds (Lon don, 1893-96) ; Oiscaux fossiles de la France (Paris, 1867-71) : Marsh, Odonto•nithcs, a graph of the artinet Toothed Birds of :Vora America (Washington, 1880) ; Lucas, Animals of the Past (New York, 1901) : Case, "The Devel opment and Zoological Relations of the Ver tebrates Aves-Mammalia," in The Journal of Geology (Chicago, 1898). See also, for further references and pal ticulars, Bums; ExTiscr ANI MALS; ARCILEOPTERYN; BESPERORNIS ; aloes, eta,