Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
         Amniota Haeckel, 1866 [Gauthier, Kluge & Rowe 1988] - amniotes
           Class Reptilia Linnaeus, 1758 [paraphyletic] - reptiles
             Subclass †Synapsida Osborn, 1903 - synapsids see Class Synapsida Osborn, 1903
               Order †Therapsida Broom, 1905 see [unranked] Therapsida Broom, 1905
                 Suborder †Gorgonopsia Seeley, 1894 see [unranked] Gorgonopsia Seeley, 1894
                   ?Family †Hipposauridae Watson & Romer, 1956