Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
   Subclass Ornithurae Haeckel, 1866 see Clade Ornithurae Haeckel 1866 [Gauthier 1986] {Chiappe 1991}
     Infraclass Ratitae (Merrem, 1813) P. Brodkorb, 1963 see Parvclass Ratitae (Merrem, 1813)
       1 Order Struthioniformes Latham, 1790
       2 Order Rheiformes Forbes, 1884 see Suborder Rheae Forbes, 1884
       3 Order Casuariiformes Sclater, 1880
       4 Order ‡Aepyornithiformes Newton, 1884
       5 Order ‡Dinornithiformes Gadow, 1893 - moas
       6 Order Apterygiformes Haeckel, 1866