Mammalia Linnaeus, 1758 - mammals
   Cetartiodactyla Montgelard, Catzeflis & Douzery 1997 see Order Cetartiodactyla Montgelard, Catzeflis & Douzery, 1997
     Cetancodonta Arnason, Gullberg, Gretarsdottir, Ursing & Janke 2000
       Hippopotamoidea Gentry & Hooker 1988 [Boisserie 2007]
         Family Hippopotamidae Gray, 1821 - hippopotamuses
           Subfamily Hippopotaminae Gray, 1821
             Genus †Hexaprotodon Falconer & Cautley, 1836
               †Hexaprotodon iravaticus Falconer & Cautley, 1847
               1 †Hexaprotodon? sahabiensis Gaziry, 1987
               2 †Hexaprotodon? hipponensis (Gaudry, 1876)
               3 †Hexaprotodon? imaguncula (Hopwood, 1926)
               4.1? †Hexaprotodon garyam (Boisserie et al., 2005)
               4.2.1 †Hexaprotodon sivalensisᵀ (Falconer & Cautley, 1836)
               4.2.2 †Hexaprotodon bruneti Boisserie & White, 2004