Neornithes Gadow, 1893 - living birds
   Palaeognathae - palaeognaths see Cohort Palaeognathae Pycraft, 1900
     ratites see Subcohort Ratitae Merrem, 1813
       Family Rheidae Bonaparte, 1849 - rheas
         Genus Rhea Brisson, 1760 [monotypic]
           Rhea americana (Linnaeus, 1758) - greater rhea
             1 Rhea americana americanaᵀ (Linnaeus, 1758)
             2 Rhea americana intermedia Rothschild & Chubb, 1914
             3 Rhea americana nobilis Brodkorb, 1939
             4 Rhea americana araneipes Brodkorb, 1938
             5 Rhea americana albescens Lynch Arribálzaga & Holmberg, 1878