Synapsida

Mounted skeleton of Edaphosaurus at the Field Museum of Natural History, Chicago, photographed by Jason Cross.


Belongs within: Reptiliomorpha.
Contains: Therapsida.

The Synapsida is the total group for mammals—that is, mammals and all fossil animals more closely related to mammals than to reptiles. The most basal synapsids, the Permian 'pelycosaurs', were still fairly 'reptilian' in their general appearance, and include such well-known exemplars as the carnivorous Dimetrodon and the herbivorous Edaphosaurus.

Synapomorphies (from Kemp 1988): Temporal fenestra bounded above by squamosal and postorbital; occipital plate broad and tilted forwards; post-temporal fenestra small; postparietal single and median; septomaxilla with broad base and dorsal process; medial process of jugal sutured to pterygoid, ectopterygoid primitively present.

<==Synapsida [Edaphosauria, Ophiacodontia, Pelycosauria, Sphenacodontia, Theromorpha, Theropsida]
    |  i. s.: Varanosaurus GKR88
    |         Protoclepsydrops LR95
    |         Mycterosaurus longiceps M06
    |         Archaeothyris florensis M06
    |         Oedaleops GKR88
    |--+--Eothyris LR95 [Eothyrididae K88]
    |  `--Caseidae K88
    `--+--Varanopseidae K88
       |    |--Basicranodon fortsillensis M06
       |    |--Archaeovenator hamiltonensis D-SMS06
       |    |--Mesenosaurus romeri D-SMS06
       |    |--Elliotsmithia longiceps MS01
       |    |--Varanops brevirostris K88
       |    `--Aerosaurus GKR88
       `--+--Ophiacodon GKR88 [Ophiacodontidae K88]
          `--+--Edaphosaurus N85 [Edaphosauridae K88]
             |    `--E. poconias N85
             `--Sphenacodontidae K88
                  |  i. s.: Secodontosaurus BH04
                  |--Haptodus K88
                  `--+--Therapsida K88
                     `--Dimetrodon Cope 1878 BH04
                          |--D. grandis N85
                          |--D. limbatus BH04
                          |--D. milleri BH04
                          |--D. natalis BH04
                          |--D. occidentalis BH04
                          `--D. teutonis Berman et al. 2001 BH04

*Type species of generic name indicated

REFERENCES

[BH04] Berman, D. S., A. C. Henrici, S. S. Sumida & T. Martens. 2004. New remains of Dimetrodon teutonis (Synapsida: Sphenacodontidae) from the Lower Permian of Germany. Annals of Carnegie Museum 73 (2): 48-56.

[D-SMS06] Dias-da-Silva, S., S. P. Modesto & C. L. Schultz. 2006. New material of Procolophon (Parareptilia: Procolophonoidea) from the Lower Triassic of Brazil, with remarks on the ages of the Sanga do Cabral and Buena Vista formations of South America. Canadian Journal of Earth Sciences 43: 1685-1693.

[GKR88] Gauthier, J. A., A. G. Kluge & T. Rowe. 1988. The early evolution of the Amniota. In The Phylogeny and Classification of the Tetrapods, vol. 1. Amphibians, Reptiles, Birds (M. J. Benton, ed.) pp. 103-155. Clarendon Press: Oxford.

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

[LR95] Laurin, M., & R. R. Reisz. 1995. A reevaluation of early amniote phylogeny. Zoological Journal of the Linnean Society 113: 165-223.

[M06] Modesto, S. P. 2006. The cranial skeleton of the Early Permian aquatic reptile Mesosaurus tenuidens: implications for relationships and palaeobiology. Zoological Journal of the Linnean Society 146: 345-368.

[MS01] Modesto, S. P., & R. M. H. Smith. 2001. A new Late Permian captorhinid reptile: a first record from the South African Karoo. Journal of Vertebrate Paleontology 21 (3): 405-409.

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

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