Class Bivalvia Linnaeus, 1758 - bivalves
   Subclass Autobranchia Grobben, 1894
     Superorder Heteroconchia Gray, 1854
       Clade Heterodonta Neumayr, 1884
         †"Megalodonts"
           1 Family †Congeriomorphidae Saul, 1976
           2 Family †Dicerocardiidae Kutassy, 1934
           3 Family †Mecynodontidae Haffer, 1959
           4 Family †Megalodontidae Morris & Lycett, 1853
           5 Family †Pachyrismatidae Scarlato & Starobogatov, 1979
           6 Family †Plethocardiidae Scarlato & Starobogatov, 1979
           7 Family †Wallowaconchidae Yancey & Stanley, 1999