After Laurin, 1996a,b and Berman, Henrici, Sumida & Martens, 2000

<==o †Seymouriamorpha Watson, 1917
   |?- †“Rhipaeosaurus” talonophorus [Leptoropha novojilovi]
   |?- †Microphon exiguus Ivakhnenko, 1983 [has long been treated as a procolophonid reptile (Säilä, 2009)]
   |-- †Urumqia liudaowanensis
   |-- †Utegenia shpinari Kuznetsov & Ivakhnenko, 1981
   |--o †Kotlassiidae [incl.? Bystrowianidae Vjuschkov, 1957 ]
   |  |?-o †Axitectum Shishkin & Novikov, 1992 [Bystrowianidae]
   |  |  |-- †A. vjushkovi Shishkin & Novikov, 1992
   |  |  `-- †A. georgi Shishkin & Novikov, 1992
   |  |-- †Buzulukia
   |  |-- †Bystrowiana permira Vjuschkov, 1957 [Bystrowianidae]
   |  |?- †Dromotectum spinosum Novikov & Shishkin, 1996 [Bystrowianidae]
   |  |?- †Enosuchus breviceps
   |  |-- †Karpinskiosaurus
   |  |-- †Kotlassia
   |  `?- †Synesuchus muravjevi Novikov & Shishkin, 2000 [Bystrowianidae]
   `--+--o †Discosauriscidae Romer, 1947 sensu stricto
      |  |-- †Makowskia laticephala Klembara, 2005
      |  `--o †Discosauriscus Kuhn, 1933 [taxonomic history]
      |    |-- †D. austriacus (Makowsky, 1876) [taxonomic history]
      |    `-- †D. pulcherrimus (Fritsch, 1879) [taxonomic history]
      `--+-- †Ariekanerpeton sigalovi Ivakhnenko, 1981
         `--o †Seymouriidae
            |-- †Gnorhinosuchus
            |-- †Nyctiboetus
            |-- †Rhinosauriscus
            `--o †Seymouria L. Per. NA. Eu.
               |-- †S. agilis
               |-- †S. grandis  U. Per. NA. Eu.
               `--+-- †S. sanjuanensis L. Per. NA. Eu.
                  `-- †S. baylorensis  L. Per. NA.

Reference(s):