Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
         Amniota Haeckel, 1866 [Gauthier, Kluge & Rowe 1988] - amniotes
           Class Mammalia Linnaeus, 1758 - mammals
             Subclass Theria Parker & Haswell, 1897
               Theria of Metatherian-Eutherian grade
                 Infraclass Eutheria Gill, 1872
                   Order Rodentia Bowdich, 1821 - rodents
                     Suborder Hystricognathi Tullberg, 1899 see Infraorder Hystricognathi Tullberg, 1899
                       Infraorder Caviomorpha Wood & Patterson, 1955 see Parvorder Caviomorpha Wood & Patterson, 1955
                         Superfamily Cavioidea Fischer de Waldheim, 1817
                           Family Hydrochoeridae Gray, 1825