Therapsida

Reconstruction of Lemurosaurus pricei, by Theropsida.

Belongs within: Sphenacodontidae.
Contains: Eutherapsida.

The Therapsida are a clade including all synapsids except for the basal 'pelycosaurs', first known from the Middle Permian. Basal members of the clade include the Biarmosuchia, a group of small to medium-sized carnivores known from the Middle and Upper Permian of South Africa and Russia, characterised by the possession of uniformly small upper incisor teeth (Sidor 2003).

Synapomorphies (from Kemp 1988): Lateral temporal fenestra enlarged; supratemporal lost; shallow groove (external auditory meatus) on posterior face of squamosal; septomaxilla with long posterodorsal process; pineal foramen on raised boss; reflected lamina of angular greatly enlarged as thin sheet; jaw articulation shifted forwards; mobile basipterygoid articulation absent; interpterygoid vacuity reduced; palatal teeth reduced; paroccipital process extending more laterally than ventrally; vomer transversely widened between internal nares; transverse process of pterygoid shifted forward; no ossified intercentra in trunk; ossified sternum; cleithrum reduced, scapular blade narrow, coracoid and procoracoid reduced, screw-shaped glenoid absent; ilium expanded both anteriorly and posteriorly, acetabulum circular, fourth trochanter of femur absent; phalanges reduced.

<==Therapsida
    |--+--Eotitanosuchus [Eotitanosuchia] CL97
    |  `--Eutherapsida S03
    `--Biarmosuchia S03
         |  i. s.: Phthinosuchus Efremov 1954 K88, D07 [Phthinosuchia]
         |           |--P. discors D07
         |           `--P. horissiaki D07
         |--Biarmosuchidae TT05
         |    |--Biarmosuchoides romanovi Tverdochlebova & Ivakhnenko 1994 TT05
         |    `--Biarmosuchus Chudinov 1960 S03, D07 [incl. Biarmosaurus K88]
         |         |--B. antecessor D07
         |         |--B. tchudinovi D07
         |         `--B. tener D07
         `--+--Hipposaurus Broom 1940 S03, D07
            |    |--H. boonstrai D07
            |    `--H. seelyi D07
            `--Ictidorhinidae S03
                 |--Lycaenodon Broom 1925 [incl. Hipposauroides Boonstra 1952] S03
                 |    `--*L. longiceps Broom 1925 [incl. Hipposaurus rubidgei Broom 1940, *Hipposauroides rubidgei] S03
                 `--+--Ictidorhinus martinsi S03
                    `--Burnetiamorpha S03
                         |--Lemurosaurus pricei S03
                         `--Burnetiidae S03
                              |--Burnetia mirabilis S03
                              |--Proburnetia S03
                              `--Bullacephalus S03

Therapsida incertae sedis:
  Delphinognathus N85
  Lycaenops Colbert 1948 D07
    |--L. angusticeps D07
    `--L. ornatus D07
  Microurania [Microuraniidae] TT05
    `--M. minima Ivakhnenko 1995 TT05
  Porosteognathus [Pristerognathidae] TT05
  Scylacosuchus [Scylacosauridae] TT05
    `--S. orenburgensis TT05
  Moschorhinidae TT05
    |--Annatherapsidus petri (Amalitskii 1922) TT05
    `--Chthonosaurus velocidens V’yushkov 1955 TT05
  Titanosuchus Owen 1879 D07
    |--T. cloeti D07
    `--T. ferox D07
  Jonkeria Van Hoepen 1916 D07
    |--J. boonstrai D07
    |--J. haughtoni D07
    |--J. ingens D07
    |--J. koupensis D07
    |--J. parva D07
    |--J. rossowi D07
    |--J. truculenta D07
    `--J. vanderbyli D07
  Moschops Broom 1911 D07
    |--M. capiensis D07
    |--M. koupensis D07
    |--M. oweni D07
    `--M. whaitsi D07
  Styracocephalus Houghton 1929 D07
    `--S. platyrhynchus D07

*Type species of generic name indicated

REFERENCES

[CL97] Cheng Z. & Li J. 1997. A new genus of primitive dinocephalian—the third report on Late Permian Dashankou lower tetrapod fauna. Vertebrata PalAsiatica 35 (1): 35–43.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[K88] Kemp, T. S. 1988. Interrelationships of the Synapsida. In: Benton, M. J. (ed.) The Phylogeny and Classification of the Tetrapods vol. 2. Mammals pp. 1–22. Clarendon Press: Oxford.

[N85] Norman, D. 1985 (reprinted 2000). The Illustrated Encyclopedia of Dinosaurs. Salamander Books: London.

[S03] Sidor, C. A. 2003. The naris and palate of Lycaenodon longiceps (Therapsida: Biarmosuchia), with comments on their early evolution in the Therapsida. Journal of Paleontology 77 (5): 977–984.

[TT05] Tverdokhlebov, V. P., G. I. Tverdokhlebova, A. V. Minikh, M. V. Surkov & M. J. Benton. 2005. Upper Permian vertebrates and their sedimentological context in the South Urals, Russia. Earth-Science Reviews 69: 27–77.

Last updated: 27 August 2018.