Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
   Subclass †Sauriurae Haeckel, 1866 see Subclass Archaeornithes Gadow, 1893
     Infraclass †Enantiornithes Walker, 1981
       Order †Alexornithiformes Brodkorb, 1976
         Family †Alexornithidae Brodkorb, 1976
           1 Genus †Alexornis Brodkorb, 1976 [monotypic]
           2 Genus †Kizylkumavis Nessov, 1984
           3 Genus †Sazavis Nessov & Yarkov, 1989 [monotypic]
           4 Genus †Nanantius Molnar, 1986
           5 Genus †Gobipteryx Elżanowski, 1974 [monotypic]
           6 Genus †Neuquenornis Chiappe & Calvo, 1994
           7 Genus †Zhyraornis Nessov, 1984
           8 Genus †Lenesornis Kurochkin, 1996 [monotypic]