Eothyris

Eothyris
	Drawing life reconstruction of Eothyris
Temporal occurrence
	Unterperm ( Sacmarium )
	295.5 to 290.1 million years
Locations
	Archer County ( Texas , USA );
Systematics
	Amniotes (Amniota)
	Synapsids (Synapsida)
	Caseasauria
	Eothyrididae
	Eothyris
Scientific name
	Eothyris
	Romer , 1937
Art
	Eothyris parkeyi;

Eothyris is an extinct genus of synapsids fromthe Eothyrididae family . The holotype and at the same time the only known specimen of the only species Eothyris parkeyi is a skull from the Petrolia Formation (at that time the Belle Plains Formation) of the Lower Permian of North Texas, whichwas scientifically describedby Alfred Romer in 1937. The closest related genus is Oedaleops .

description

Drawing reconstruction of the head of Eothyris

The skull of Eothyris is about 6 cm long. The body reached a length of less than 1 m. The upper jaw was equipped with two large canine-like teeth that had no counterpart in the lower jaw. Teeth of a similar type were much smaller in Oedaleops , although the latter was of a comparable size. From the structure of the remaining teeth one can conclude that Eothyris was an insect eater .

Systematics

Eothyris forms with Oedaleops the family of the Eothyrididae . This is considered to be the sister taxon of the Caseidae , a group of herbivorous, medium-sized synapsids with a barrel-shaped body. The Eothyrididae and Caseidae are referred to as Caseasauria , which are considered the most basal group of synapsids and the sister taxon of Eupelycosauria . The Eupelycosauria, the more basal groups of which, together with the Caseasauria, are also known as " Pelycosaurians ", include the well-known "dorsal sail synapsids" such as Dimetrodon and Edaphosaurus as well as mammals . The cladogram below shows the position of Eothyris within the Caseasauria (according to Maddin et al., 2008, and Reisz et al., 2009):

Caseasauria

Eothyrididae

	Eothyris

	Oedaleops

Caseidae

Oromycter

Casea

Ennatosaurus

	Cotylorhynchus

	Angelosaurus

Individual evidence

^ Alfred Sherwood Romer: New genera and species of pelycosaurian reptiles. Proceedings of the New England Zoological Club. Vol. 16, 1937, pp. 89-95.
^ ^A ^b Robert R. Reisz, Stephen J. Godfrey, Diane Scott: Eothyris and Oedaleops : Do These Early Permian Synapsids from Texas and New Mexico form a Clade? Journal of Vertebrate Paleontology. Vol. 29, No. 1, 2009, pp. 39-47, doi : 10.1671 / 039.029.0112 , JSTOR 20491067 .
↑ ^a ^b Thomas S. Kemp: The Origin & Evolution of Mammals . Oxford University Press, Oxford 2005, ISBN 0-19-850761-5 .
↑ Hillary C. Maddin, Christian A. Sidor, Robert R. Reisz: Cranial Anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the Evolutionary Relationships of Caseidae. Journal of Vertebrate Paleontology. Vol. 28, No. 1, 2008, pp. 160–180, doi : 10.1671 / 0272-4634 (2008) 28 [160: CAOETS] 2.0.CO; 2 , JSTOR 30126342 ( alternative download , PDF 3.2 MB) .

Web links

Commons : Eothyris - Collection of images, videos and audio files

[1] Alfred Sherwood Romer: New genera and species of pelycosaurian reptiles. Proceedings of the New England Zoological Club. Vol. 16, 1937, pp. 89-95.

[reisz09-2] A ^b Robert R. Reisz, Stephen J. Godfrey, Diane Scott: Eothyris and Oedaleops : Do These Early Permian Synapsids from Texas and New Mexico form a Clade? Journal of Vertebrate Paleontology. Vol. 29, No. 1, 2009, pp. 39-47, doi : 10.1671 / 039.029.0112 , JSTOR 20491067 .

[Kemp2005-3] Thomas S. Kemp: The Origin & Evolution of Mammals . Oxford University Press, Oxford 2005, ISBN 0-19-850761-5 .

[Maddinetal-4] Hillary C. Maddin, Christian A. Sidor, Robert R. Reisz: Cranial Anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the Evolutionary Relationships of Caseidae. Journal of Vertebrate Paleontology. Vol. 28, No. 1, 2008, pp. 160–180, doi : 10.1671 / 0272-4634 (2008) 28 [160: CAOETS] 2.0.CO; 2 , JSTOR 30126342 ( alternative download , PDF 3.2 MB) .