vertebrates Cuvier, 1812 - vertebrates
   Cohort Amniota Haeckel, 1866 see Clade Amniota Haeckel, 1866 [Gauthier, Kluge & Rowe 1988]
     Class "Reptilia" Linnaeus, 1758 - reptiles
       Subclass Sauropsida Huxley, 1864
         Superorder †Euryapsida Colbert, 1945
           Order †Sauropterygia Owen, 1860 see Superorder Sauropterygia Owen, 1860
             Suborder †Plesiosauria Blainville, 1835 see Order Plesiosauria Blainville, 1835
               Superfamily †Pliosauroidea Welles, 1943 see Suborder Pliosauroidea Welles, 1943
                 Family †Polycotylidae Williston, 1908