Imperium naturæ C. Linnaeus, 1758 - nature
   Mundus Plinius - physical world
     naturalia - natural bodies
       Regnum Animale C. Linnaeus, 1758 - animal kingdom see Kingdom Animalia Linnaeus, 1758
         Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
           Order Grallae Linnaeus, 1758
             Genus Otis Linnaeus, 1758
               1 Otis tarda Linnaeus, 1758 - great bustard
               2 Otis arabs Linnaeus, 1758 see Ardeotis arabs (Linnaeus, 1758)
               3 Otis tetrax Linnaeus, 1758 see Tetrax tetrax (Linnaeus, 1758)
               4 Otis afra Linnaeus, 1758 see Afrotis afra (Linnaeus, 1758)