organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Eukaryota Chatton, 1925 - eukaryotes see Domain Eukaryota Chatton, 1925
     Kingdom Animalia Linnaeus, 1758 - animals
       Deuterostomia Grobben, 1908 - deuterostomes see Infrakingdom Deuterostomia Grobben, 1908
         Phylum Chordata Bateson, 1885 - chordates
           Subphylum Vertebrata Cuvier, 1812 - vertebrates
             Superclass Tetrapoda Goodrich, 1930 - tetrapods see Clade Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
               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 †Eothyrididae Romer & Price, 1940
                     3 Family †Caseidae Williston, 1912
                     4 Family †Edaphosauridae Cope, 1882
                     5 Family †Varanopidae Romer & Price, 1940
                     6 Family †Sphenacodontidae Marsh, 1878