Class Bivalvia Linnaeus, 1758 - bivalves Subclass Autobranchia Grobben, 1894 Superorder Pteriomorphia Beurlen, 1944 Order †Cyrtodontida Scarlato & Starobogatov, 1971 Superfamily †Cyrtodontoidea Ulrich, 1894 1 Family †Cyrtodontidae Ulrich, 1894 2 Family †Ptychodesmatidae Scarlato & Starobogatov, 1984