Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758 Pygostylia Chatterjee 1997 [Chiappe 2001] Ornithothoraces Chiappe 1995 †Enantiornithes Walker 1981 [Sereno 1998] see Infraclass Enantiornithes Walker, 1981 Genus †Neuquenornis Chiappe & Calvo, 1994