[Avialae] Gauthier 1986 Aves Linnaeus 1758 [Gauthier 1986], nom. cl. inval. see Subclass Aves Linnaeus, 1758 Pygostylia Chatterjee 1997 [Chiappe 2001] Ornithothoraces Chiappe 1995 Ornithuromorpha Chiappe 2001 Ornithurae Haeckel 1866 [Gauthier 1986] {Chiappe 1991} Genus †Ichthyornis Marsh, 1872