Class Mammalia Linnaeus, 1758 - mammals Subclass Acrotheria Averianov & Lopatin, 2011 Infraclass †"Symmetrodonta" Simpson, 1925 [paraphyletic] Order †Spalacotheriida Prothero, 1981 [sister group to excluded taxa] Family †Zhangheotheriidae Rougier, Ji & Novacek, 2003