Phylum Brachiopoda Duméril, 1806 - brachiopods
   Subphylum Rhynchonelliformea Williams et al., 1996
     Class Rhynchonellata Williams et al., 1996
       Order †Protorthida Schuchert & Cooper, 1931
         Superfamily †Protorthoidea Schuchert & Cooper, 1931
           1 Family †Protorthidae Schuchert & Cooper, 1931
           2 Family †Arctohedridae Williams et al., 2000
           3 Family †Leioriidae Cooper, 1976