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ODONTORNITHES

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Originally appearing in Volume V20, Page 10 of the 1911 Encyclopedia Britannica.
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ODONTORNITHES , the See also:

term proposed by O. C. See also:Marsh (Am. Journ. Sci. See also:ser 3, V. (1873) pp. 161–162) for birds possessed of See also:teeth (Gr. Mobs, tooth, 6pvcs, 6pvLOos, See also:bird), notably the genera Hesperornis and Ichthyornis from the Cretaceous deposits of See also:Kansas. In 1875 (op. Cit. X. pp. 403–408) he divided the " subclass " into See also:Odontolcae, with the teeth See also:standing in grooves, and Odontotormae, with the teeth in See also:separate alveoles or sockets.

In his magnificent See also:

work, C.iontornithes: A monograph on the See also:extinct toothed birds of See also:North See also:America, New Haven, See also:Connecticut, 188o, he logically added the Saururae, represented by See also:Archaeopteryx, as a third See also:order. As it usually happens with the selection of a single anatomical See also:character, the resulting See also:classification was unnatural. In the See also:present See also:case the Odontornithes are a heterogeneous See also:assembly, and the fact of their possessing teeth proves nothing but that birds, possibly all of them, still had these See also:organs during the Cretaceous See also:epoch. This, by itself, is a very interesting point, showing that birds, as a class, are the descendants of well-toothed See also:reptiles, to the See also:complete exclusion of the Chelonia with which various authors persistently try to connect them. No fossil birds of later than Cretaceous See also:age are known to have teeth, and concerning See also:recent birds they possess not even embryonic vestiges. E. See also:Geoffroy St Hilaire stated in 1821 (See also:Ann. Gen. Sci. Phys. viii. pp. 373–380) that he had found a considerable number of tooth-germs in the upper and See also:lower jaws of the See also:parrot Palaeornis torquatus. E.

See also:

Blanchard (" Observations sur le systeme dentaire chez See also:les oiseaux," Comptes rendus 50, 186o, pp. 540-542) See also:felt justified in recognizing flakes of dentine. However, M. Braun (Arbeit Zool. Inst., Wiirzhurg, v. 1879) and especially P. Fraisse (Phys. Med. Ges., Wiirzburg, 188o) have shown that the structures in question are of the same See also:kind as the well-known serrated teeth " of the See also:bill of anserine birds. In fact the papillae observed in the embryonic birds are the soft cutaneous extensions into the surrounding horny sheath of the bill, comparable to the well-known nutritive papillae in a See also:horse's hoof. They are easily exposed in the well-macerated under See also:jaw of a parrot, after removal of the horny sheath. Occasionally calcification occurs in or around these papillae, as it does regularly in the " See also:egg-tooth " of the embryos of all birds.

The best known of the Odontornithes are Hesperornis regalis, standing about 3 ft. high, and the somewhat taller H. crassipes. Both show the See also:

general configuration of a See also:diver, but it is only by See also:analogy that Hesperornis can be looked upon as ancestral to the Colymbiformes. There are about fourteen teeth in a groove of the maxilla and about twenty-one in the mandible; the vertebrae are typically heterocoelous; of the wing-bones only the very slender and See also:long humerus is known; clavicles slightly reduced; coracoids See also:short and broad, movably connected with the scapula; sternum very long, broad and quite See also:flat, without the trace of a See also:keel. See also:Hind limbs very strong and of the Colymbine type, but the See also:outer or See also:fourth capitulum of the metatarsus is the strongest and longest, an unique arrangement in an otherwise typically steganopodous See also:foot. The See also:pelvis shows much resemblance to that of the See also:divers, but there is still an incisura ischiadica instead of a foramen. The tail is composed of about twelve vertebrae, without a pygostyle. Enaliornis of the See also:Cambridge See also:Greensand of See also:England, and Baptornis of the See also:mid-Cretaceous of North America, are probably allied, but imperfectly known. The vertebrae are biconcave, with heterocoelous indications in the cervicals; the metatarsal bones appear still somewhat imperfectly anchylosed. The See also:absence of a keel misled Marsh who suspected relationship of Hesperornis with the See also:Ratitae, and L. Dollo went so far as to See also:call it a carnivorous, aquatic See also:ostrich (See also:Bull. Sci. Depart. du See also:Nord, ser.

2, iv. 1881, p. 300), and this mistaken notion of the " See also:

swimming ostrich " was popularized by various authors. B. See also:Vetter (Festschr. Ges. See also:Isis., See also:Dresden, 1885) rightly pointed out that Hesperornis was a descendant of Carinatae, but adapted to aquatic See also:life, implying reduction of the keel. Lastly, M. Fiirbringer (Untersuchungen, See also:Amsterdam, 1888, pp. 1543, 1505, 1580) relegated it, together with Enaliornis and the Colymbo-Podicipedes, to his suborder Podicipitiformes. The present writer does not feel justified in going so far. On See also:account of their various, decidedly See also:primitive characters, he prefers to look upon the Odontolcae as a separate See also:group, one of the three divisions of the Neornithes, as birds which See also:form an See also:early offshoot from the later Colymbo-Pelargomorphous stock; in See also:adaptation to a marine, swimming life they have lost the See also:power of See also:flight, as is shown by the absence of the keel and by the See also:great reduction of the wing-See also:skeleton, just as in another direction, away from the later Alectoromorphous stock the Ratitae have specialized as runners.

It is only in so far as the loss of flight is correlated with the absence of the keel that the Odontolcae and the Ratitae See also:

bear analogy to each other. There remain the Odontotormae, notably Ichthyornis See also:victor, I. dispar, Apatornis and Graculavus of the See also:middle and upper Cretaceous of Kansas. The teeth stand in separate alveoles; the two halves of the mandible are, as in Hesperornis, without a symphysis. The vertebrae are amphicoelous, but at least the third cervical has somewhat See also:saddle-shaped articular facets. Tail composed of five See also:free vertebrae, followed by a rather small pygostyle. See also:Shoulder See also:girdle and sternum well See also:developed and of the typical carinate type. Pelvis still with incisura ischiadica. Marsh based the restoration of Ichthyornis, which was obviously a well-flying aquatic bird, upon the skeleton of a See also:tern, a relation-See also:ship which cannot be supported. The teeth, vertebrae, pelvis and the small See also:brain are all so many See also:low characters that the Odontotormae may well form a separate, and very low, order of the typical Carinatae, of course near the Colymbomorphouu See also:Legion. (H. F.

End of Article: ODONTORNITHES

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