Phylum [Vertebrata] Lamarck, 1801 see Infraphylum Vertebrata Lamarck, 1801
   Class Reptilia Linnaeus, 1758 - reptiles
     Subclass †Synapsida Osborn, 1903 - synapsids see Class Synapsida Osborn, 1903
       Order †Pelycosauria Cope, 1878 - pelycosaurs
         1 Family †Ophiacodontidae Nopsca, 1923
         2 Family †Caseidae Williston, 1912
         3 Family †Edaphosauridae Cope, 1882
         4 Family †Sphenacodontidae Marsh, 1878
         5 Family †uncertain