[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Vertebrata Lamarck, 1801 see Infraphylum Vertebrata Lamarck, 1801
         Branch Craniata Linnaeus, 1758
           Grade Gnathostoma
             Subgrade Pentadactyla lipobranchia
               Branch Monocondyla
                 Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
                   Order Ratitæ (Merrem, 1813)
                     Genus Apteryx Shaw, 1813