Class Bivalvia Linnaeus, 1758 - bivalves Subclass Autobranchia Grobben, 1894 Superorder Heteroconchia Gray, 1854 Clade Heterodonta Neumayr, 1884 Order †Orthonotida Pojeta, 1978 [monotypic] Superfamily †Orthonotoidea Miller, 1877 ?Family †Prothyridae Miller, 1889