Cetacea/Artiodactyla Montgelard, Catzeflis & Douzery 1997 see Order Cetartiodactyla Montgelard, Catzeflis & Douzery, 1997
   Family †Mesonychidae Cope, 1875
     1 Genus †Dissacus Cope, 1881
     2.1 Genus †Ankalogon nom. null. see Genus Ankalagon van Valen, 1980
     2.2.1 Genus †Sinonyx Zhou, Zhai, Gingerich & Chen, 1995
     2.2.2.1 †Pachyaena gigantea Osborn & Wortman, 1892
     2.2.2.2 †Pachyaena ossifraga (Cope, 1874)
     2.2.2.3.1 Genus †Mesonyx Cope, 1872
     2.2.2.3.2 Genus †Synoplotherium Cope, 1872
     2.2.2.3.3 Genus †Harpagolestes Wortman, 1901