ichthyornis

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various extinct, toothed birds of the genus Ichthyornis that existed during the Cretaceous Period.

Century Dictionary and Cyclopedia

1. n. A remarkable genus of birds, founded by Marsh (1872) upon remains from the pteranodon beds, of Cretaceous age, in Kansas: so called from the resemblance of the vertebræ to those of fishes. After Archæopteryx, of Jurassic age, Ichthyornis and Hesperornis are the most notable genera in ornithology; each furnishes a type of a primary division of the class Aves, and they are collectively known as Odontornithes, or birds with teeth. Ichthyornis represents the family Ichthyornithidæ and the order or subclass Odontotormæ, or birds with socketed teeth and biconcave vertebræ. yet with developed wings, ankyloses metacarpals, carinate sternum, and short coccyx, as in modern birds. I. dispar. the leading species, was about as large as a pigeon. Several other species are also described.

GNU Webster's 1913

1. n. (Paleon.) An extinct genus of toothed birds found in the American Cretaceous formation. It is remarkable for having biconcave vertebræ, and sharp, conical teeth set in sockets. Its wings were well developed. It is the type of order Odontotormæ.