Class Reptilia Linnaeus, 1758 - reptiles
   Subclass †Euryapsida Colbert, 1945 see Subclass Diapsida Osborn, 1903
     Order †Sauropterygia Owen, 1860 see Superorder Sauropterygia Owen, 1860
       Suborder †Plesiosauria Blainville, 1835 see Order Plesiosauria Blainville, 1835
         1 Family †Pistosauridae Zittel, 1887
         2 Family †Pliosauridae Seeley, 1874
         3 Family †Polycotylidae Williston, 1908
         4 Family †Plesiosauridae Gray, 1825
         5 Family †Elasmosauridae Cope, 1869