organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Eukaryota Chatton, 1925 - eukaryotes see Domain Eukaryota Chatton, 1925
     Kingdom Animalia Linnaeus, 1758 - animals
       Deuterostomia Grobben, 1908 - deuterostomes see Infrakingdom Deuterostomia Grobben, 1908
         Phylum Chordata Bateson, 1885 - chordates
           Subphylum Vertebrata Cuvier, 1812 - vertebrates
             Superclass Tetrapoda Goodrich, 1930 - tetrapods see Clade Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
               Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
                 Subclass †Archaeornithes Gadow, 1893 see Superorder Archaeornithes Gadow, 1893
                   01 Order †Archaeopterygiformes Fürbringer, 1888
                   02 Order †Confuciusornithiformes Hou, Zhou, Gu & Zhang, 1995
                   03 Order †Iberomesornithiformes Sanz & Bonaparte, 1992
                   04 Order †Alexornithiformes Brodkorb, 1976
                   05 Order †Cathayornithiformes Zhou, Jin & Zhang, 1992
                   06 Order †Gobipterygiformes Elzanowski, 1974 see Order Alexornithiformes Brodkorb, 1976
                   07 Order †Enantiornithiformes Martin, 1983 see Order Alexornithiformes Brodkorb, 1976
                   08 Order †Liaoningornithiformes Hou, 1996
                   09 Order †Gansuiformes Hou & Liu, 1984
                   10 Order †Patagopterygiformes Alvarenga & Bonaparte, 1992
                   11 Order †Hesperornithiformes Fürbringer, 1888
                   12 Order †Ambiortiformes Kurochkin, 1982
                   13 Order †Ichthyornithiformes Marsh, 1873