[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Vertebrata (Lamarck, 1801)
         Branch Craniata Linnaeus, 1758
           Grade Gnathostoma
             Subgrade Heterodactyla branchiata
               Class Dipnoi Müller, 1844
                 Order Monopneumones
                   1 Genus Ceratodus Agassiz, 1838