hesperornithidæ

from The Century Dictionary.

• A family of fossil birds from the Cretaceous of North America, typified by the genus Hesperornis, and representing a prime division of the whole class Aves, having teeth implanted in grooves, saddle-shaped or heterocœlous vertebræ, ratite sternum, rudimentary wings, and short tail: conterminous with the subclass Odontoleæ.