Class [Mammalia] Linnaeus, 1758 - mammals Order †Plesiadapiformes Simons & Tattersall, 1972 see Suborder Plesiadapiformes Simons & Tattersall, 1972 Superfamily †Microsyopoidea Osborn & Wortman, 1892 Family †Palaechthonidae Szalay, 1969 Genus †Palaechthon Gidley, 1923 †Palaechthon alticuspis Gidley, 1923