Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
         Amniota Haeckel, 1866 [Gauthier, Kluge & Rowe 1988] - amniotes
           Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
             Subclass Neornithes Gadow, 1893 see Clade Neornithes Gadow, 1893
               Superorder Neognathae Pycraft, 1900 see Cohort Neognathae Pycraft, 1900
                 Order Anseriformes Wagler, 1831 - waterfowl and screamers
                   1 Family †Presbyornithidae Wetmore, 1926
                   2 Family Anatidae Vigors, 1825 - ducks, geese, swans
                   3 Family Anhimidae Stejneger, 1885 - screamers