Class Bivalvia Linnaeus, 1758 - bivalves Subclass Autobranchia Grobben, 1894 Superorder Heteroconchia Gray, 1854 Clade Palaeoheterodonta Newell, 1965 Order Trigoniida Dall, 1889 Superfamily †Megatrigonioidea van Hoepen, 1929 Family †Megatrigoniidae van Hoepen, 1929 Subfamily †Megatrigoniinae van Hoepen, 1929