Class Mammalia Linnaeus, 1758 - mammals Subclass Theria Parker & Haswell, 1897 Order Artiodactyla Owen, 1848 - even-toed ungulates see Order Cetartiodactyla Montgelard, Catzeflis & Douzery, 1997 Family Hippopotamidae Gray, 1821 - hippopotamuses Genus Hippopotamus Linnaeus, 1758 [monotypic] - hippopotamus ‡Hippopotamus laloumena Faure & Guérin, 1990