Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758 Subclass †Odontoholcae (Marsh, 1875) Stejneger, 1885 see Cohort Ornithurae Haeckel, 1866 Order †Hesperornithiformes Fürbringer, 1888 Family †Hesperornithidae Marsh, 1872 Genus †Hesperornis Marsh, 1872 †Hesperornis crassipes (Marsh, 1876)