Class Bivalvia Linnaeus, 1758 - bivalves
   Subclass Protobranchia Pelseneer, 1889
     Order Nuculida Dall, 1889 [monotypic]
       Superfamily Nuculoidea Gray, 1824
         1 Family Nuculidae Gray, 1824 - nut clams
         2 Family †Nucularcidae Pojeta & Stott, 2007
         3 Family †Palaeoconchidae Miller, 1889
         4 Family †Praenuculidae McAlester, 1969
         5 Family Sareptidae Stoliczka, 1870