Phylum Chordata Bateson, 1885 - chordates
   Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
     Subclass Neornithes Gadow, 1893 see Clade Neornithes Gadow, 1893
       Superorder Palaeognathae Pycraft, 1900 see Cohort Palaeognathae Pycraft, 1900
         Order Rheiformes Forbes, 1884 see Suborder Rheae Forbes, 1884
           Family Rheidae Bonaparte, 1849 - rheas
             Genus Pterocnemia Gray, 1871
               Pterocnemia pennata (d'Orbigny, 1834) - lesser rhea