Varanosaurus

• Texas, United States

• Varanosaurus acutirostris Broili, 1904

Varanosaurus (Greek " Waranechse " ) is a genus previously Pelycosaurier from the Lower Permian ( Artinskian to Kungurian ) of Texas and Oklahoma. The German paleontologist Ferdinand Broili published in 1904 the first scientific description of the type species Varanosaurus acutirostris.

The appearance of the approximately 1.5 meters long Varanosaurus strongly reminiscent of today's lizards, which also explains the generic name. Despite the good tradition of several fossils, little is known about the species. Besides Varanosaurus acutirostris another species was described, Varanosaurus wichitaensis, but with high probability as a synonym of Varanosaurus acutirostris.

Description

From Varanosaurus are two fossil skull in good condition and other postcranial elements. The skull is elongated, low and narrow. As with other members of the Ophiacodontidae the skull area of the eye socket to the tip of the snout ( the antorbitale area ) is more than twice as long as the location behind the eye sockets ( postorbital ) part of the skull. The cranial window was compared with that of other synapsids relatively small.

The upper jaw was quite narrow, pointed and slightly busy with a number of backward curved teeth and two larger fangs in the front, which suggest a predatory diet. In the lower jaw about 60 small, uniform teeth were without much size variations.

The vertebral arch obtained are robust and have a " swollen ", the spinous processes vary partly in their height and structure. The spine of Varanosaurus thus resembled that of primitive tetrapods as Diadectes, Seymouria or Captorhinidae, but this is due to convergence. Probably gave such a texture of the vertebrae along with the nearly horizontal orientation of the facet joints to the animal a greater agility in the hunt, as the tack welded to the high spinous back muscles could run freely about the low spinous processes.

Varanosaurus probably lived in swamps and fed on fish.

Classification

On the position of Varanosaurus within the Eupelycosaurier there is no final clarity. Due to the many anatomical similarities with Ophiacodon most scientists expect a close relationship between the two genera and organize Varanosaurus the Ophiacodontidae to. In some plants, the genus which however is also the Varanopseidae, not to point out the close relationship to Ophiacodon without, however.

Synonyms

There are two synonyms for Varanosaurus acutirostris. 1917 Ermine Cowles Case of Poecilospondylus Francisi ( 1871-1953 ) described, but later identified by Alfred Sherwood Romer ( 1894-1973 ) as a junior synonym of Varanosaurus acutirostris. Romer himself described in 1937 based on a hip bone as another type Varanosaurus wichitaensis due to the opposite V. acutirostris smaller size and the previous occurrence in time. The validity of this kind is, however, questioned. With high probability, it is a synonym of the type species.

Samuel Wendell Williston in 1911 Varanops brevirostris arranged initially erroneously as Varanosaurus brevirostris of the genus Varanosaurus. However, a few years later he corrected his mistake and put Varanops brevirostris as type species in its own genus Varanops.