Eothyrididae

Taxobox
name = Eothyrididae
fossil_range = Early Permian

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image_width = 250px
image_caption = life restoration of "Eothyris parkeyi", body shape is conjectural since only the skull is known
regnum = Animalia
phylum = Chordata
subphylum = Vertebrata
classis = Synapsida
ordo = Pelycosauria
subordo = Caseasauria
familia = Eothyrididae
familia_authority = Romer and Price, 1940
subdivision_ranks = Genera
subdivision = "Eothyris" "Oedaleops"The Eothyrididae were a small group of very primitive, insectivorous synapsids. Only two genera are known, Eothyris and Oedaleops, both from the early Permian of North America. Their main distinguishing feature is the large caniniform tooth in from of the maxilla.

Eothyridids share with the Caseidae a number of specialised features associated with the morphology of the snout and external naris and it is likely that they were ancestral to them. The two together form the clade Caseasauria.

Until now only the skulls of two species are long were well known, "Eothyris" and "Oedaleops", that respectively approximately 6 centimeter that the total length of the animals under 1 meter amounted to. The skulls are characterized through an incidentally wide, flat form and a large skull window. In the waiter jaw, two were enlarged in "Eothyris" per jaw half, are eyetooth good teeth, that without counterpart in the lower jaw - in "Oedaleops" by far more weakly were stamped these teeth. The remaining teeth are uniform, small and sharpened, assuming that meat or insects are the nourishment of the Eothyrididae. Of the remaining body, no fossils were found until now.

Both species are only out of the lower Permian well known out of North America. Systematically the Eothyrididae with the Caseidae form stands the group of the Caseasauria that at the basis of the Synapsids and forms that the sister group of the Eupelycosauria, out of which the Therapsids (the "mammal-like reptiles") evolved.

ee also

* Evolution of mammals

References

* Carroll, R. L. (1988), "Vertebrate Paleontology and Evolution", WH Freeman & Co.
* Reisz, R. R., 1986, "Handbuch der Paläoherpetologie – Encyclopedia of Paleoherpetology, Part 17A Pelycosauria" Verlag Dr. Friedrich Pfeil, ISBN 3-89937-032-5
* Romer, AS & Price L.I (1940), Review of the Pelycosauria. "Geol. Soc. Amer. Spec. Papers" 28: 1-538.

External links

* [http://tolweb.org/notes/?note_id=466 Tree of Life]
* [http://www.palaeos.com/Vertebrates/Units/Unit390/100.html Palaeos Vertebrates 390.100 Synapsida]
* [http://www.kheper.net/evolution/pelycosauria/Eothyrididae.html Kheper.net]