Caseasaur Fossil range: Early Permian - Late Permian PreЄ Є O S D C P T J K Pg N
Ennatosaurus tecton from the Late Permian of Russia
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Synapsida
Order:	Pelycosauria
Suborder:	Caseasauria Williston, 1912
Genera and Families
Caseidae Eothyrididae ?Phreatophasma

The Caseasauria are one of the two main clades of early synapsids, the other being the Eupelycosauria. They are currently known only from the Permian, and include two superficially different families, the small insectivorous or carnivorous Eothyrididae, and the large herbivorous Caseidae

These two groups share a number of specialised features associated with the morphology of the snout and external naris and it is likely that the latter evolved from the former.

The ancestors of Caseasaurs can be traced back from an insect eating or an omnivorous reptile-like synapsid from the Pennsylvanian time of the Carboniferous, that resembles Archaeothyris. The Caseasaurs were abundant and successful during the later part of the early Permian epoch. But by the middle Permian, the Caseasaurs became less abundant because of the evolving, more successful therapsids and by late Permian, they were facing extinction. The last Caseasaurs became extinct in the Permian–Triassic extinction event; no species of Caseasaurs made it to the Triassic Period.

[edit] See also

• Evolution of mammals
• Vertebrate paleontology
• Permian tetrapods

[edit] References

• Reisz, R. R., 1986, Handbuch der Paläoherpetologie – Encyclopedia of Paleoherpetology, Part 17A Pelycosauria Verlag Dr. Friedrich Pfeil, ISBN 3-89937-032-5
• Laurin, M. and Reisz, R. R., 1997, Autapomorphies of the main clades of synapsids

[edit] External links

• Palaeos Vertebrates 390.100 Synapsida

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