Class Mammalia Linnaeus, 1758 - mammals Subclass Acrotheria Averianov & Lopatin, 2011 Infraclass †"Symmetrodonta" Simpson, 1925 [paraphyletic] 1-n2 Order †Tinodontida Prothero, 1981 [sister group to excluded taxa] [monotypic] 2-n2.1 Order †Spalacotheriida Prothero, 1981 [sister group to excluded taxa]