Varanops

Varanops
	Skeletal reconstruction of Varanops brevirostris in the Museum of Natural History (University of Michigan)
Temporal occurrence
	Unterperm
	275.6 to 270.6 million years
Locations
	United States;
Systematics
	Land vertebrates (Tetrapoda)
	Synapsids (Synapsida)
	Eupelycosauria
	Varanopidae
	Varanodontinae
	Varanops
Scientific name
	Varanops
	Williston , 1914
Art
	Varanops brevirostris Williston, 1911 ;

Varanops ( Greek for "Warangesface") is an extinct genus of varanopid synapsids from the early Permian of Texas and Oklahoma . The animal, over a meter long, was reminiscent of the monitor lizards living todayand probably fed on small vertebrates. In 1911 by Samuel W. Williston initially described as a second species of the genus Varanosaurus , Williston revised his view in 1914 and assigned the species Varanops brevirostris as a type species of his own genus Varanops .

While most of the pelycosaurs were already extinct earlier, Varanops survived into the Kungurium and was one of the last representatives of this group. At the beginning of the late Permian, Varanops also died out, possibly due to competition from Diapsids and Therapsids .

Locations

Well-preserved fossils of Varanops have been found in the Cacops - Bonebed of the Arroyo Formation , part of the Clear Fork Group , in Baylor County , Texas. Another three specimens come from the Garber Formation , part of the Sumner Group, in Comanche County , Oklahoma. A specimen was also discovered in the Vale Formation of the Clear Fork Group, Taylor County , Texas. The specimen from the Arroyo Formation shows bite marks that indicate a large, scavenging tetrapod. With some probability it was a dissorophoid from the group of Temnospondyli . This can be inferred from the nature of the bite marks and a remarkably well-preserved dental crown stuck in the fossil's forelimbs.

description

Varanops is known to have three complete skulls in poor condition and one skull that is well preserved in parts. The largest specimen has a lower jaw with a length of 170 mm, which was occupied with 24-28 teeth. In addition, three vacant tooth sockets (alveoli) were found on both sides of the lower jaw.

Artist's impression of Varanops brevirostris

Varanops was a relatively large varanodontine varanopid, but the skull appears comparatively short. Varanops had a pointed snout, which was narrow in the front part, but widened to the rear (posterior). As in other Varanopsidae, the occiput is inclined forward. A large infratemporal window was also available.

The intermaxillary bone with six teeth is rounded, similar to the derived forms of the Ophiacodontidae and Sphenacodontidae . The central front teeth were longer than the side (lateral) teeth. In contrast to the Myctosaurinae, there were no serrations on the teeth . This trait is shared by Varanops with other varanodontins such as Varanodon and Aerosaurus .

The neck ribs were not very stable, in contrast to the back ribs, which also became larger.

classification

Varanops represents the type genus of the Varanopidae . A cladistic analysis by Campione and Reisz suggests that Varanops was a derived form of the Varadontiden, a sister taxon of the clade, which is formed from Varanodon and Watongia .

Individual evidence

↑ Samuel W. Williston (1914): "The Osteology of some American Permian Vertebrates", in: Contributions of the Walker Museum 1, pp. 107-162.
↑ ^a ^b ^c ^d ^e ^f Nicolás E. Campione and Robert R. Reisz (2010): "Varanops brevirostris (Eupelycosauria: Varanopidae) from the Lower Permian of Texas, with discussion of varanopid morphology and interrelationships", in: Journal of Vertebrate Paleontology 30 (3), pp. 724-746.
↑ Hillary C. Maddin, David C. Evans and Robert R. Reisz (2006): "An Early Permian varanodontine varanopid (Synapsida: Eupelycosauria) from the Richards Spur locality, Oklahoma", in: Journal of Vertebrate Paleontology 26 (4), Pp. 957-966.
^ Robert R. Reisz and Linda A. Tsuji (2006). "An Articulated Skeleton of Varanops with Bite Marks: the Oldest Known Evidence of Scavenging among Terrestrial Vertebrates". Journal of Vertebrate Paleontology 26 (4): 1021-1023.

literature

Samuel W. Williston (1911): "American Permian Vertebrates". University of Chicago Press, Chicago, pp. 130ff.
Nicolás E. Campione and Robert R. Reisz (2010): "Varanops brevirostris (Eupelycosauria: Varanopidae) from the Lower Permian of Texas, with discussion of varanopid morphology and interrelationships", in: Journal of Vertebrate Paleontology 30 (3), p. 724-746.
Robert R. Reisz and Linda A. Tsuji (2006): "An articulated skeleton of Varanops with bite marks: the oldest known evidence of scavenging among terrestrial vertebrates", in: Journal of Vertebrate Paleontology 26 (4), pp. 1021-1023 .
Hillary C. Maddin, David C. Evans and Robert R. Reisz (2006): "An Early Permian varanodontine varanopid (Synapsida: Eupelycosauria) from the Richards Spur locality, Oklahoma", in: Journal of Vertebrate Paleontology 26 (4), p 957-966.

Web links

Commons : Varanops - collection of images, videos and audio files

[1] Samuel W. Williston (1914): "The Osteology of some American Permian Vertebrates", in: Contributions of the Walker Museum 1, pp. 107-162.

[Reisz2010-2] ↑ ^a ^b ^c ^d ^e ^f Nicolás E. Campione and Robert R. Reisz (2010): "Varanops brevirostris (Eupelycosauria: Varanopidae) from the Lower Permian of Texas, with discussion of varanopid morphology and interrelationships", in: Journal of Vertebrate Paleontology 30 (3), pp. 724-746.

[Maddin2006-3] Hillary C. Maddin, David C. Evans and Robert R. Reisz (2006): "An Early Permian varanodontine varanopid (Synapsida: Eupelycosauria) from the Richards Spur locality, Oklahoma", in: Journal of Vertebrate Paleontology 26 (4), Pp. 957-966.

[Reisz2006-4] Robert R. Reisz and Linda A. Tsuji (2006). "An Articulated Skeleton of Varanops with Bite Marks: the Oldest Known Evidence of Scavenging among Terrestrial Vertebrates". Journal of Vertebrate Paleontology 26 (4): 1021-1023.