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 †Pelycosauria Cope, 1878 - pelycosaurs
                 Family †Sphenacodontidae Marsh, 1878