Phylum [Vertebrata] (Lamarck, 1801)
   Class Reptilia Linnaeus, 1758 - reptiles
     Subclass †Synapsida Osborn, 1903 - synapsids see Class Synapsida Osborn, 1903
       Order †Pelycosauria Cope, 1878 - pelycosaurs
         Family †Sphenacodontidae Marsh, 1878
           Genus †Dimetrodon Cope, 1878
           Genus †Sphenacodon Marsh, 1878