Ivantosaurus

Ivantosaurus Temporal range: Wordian,
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subclass:	Synapsida
Order:	Therapsida
Suborder:	†Biarmosuchia
Family:	†Eotitanosuchidae
Genus:	†Ivantosaurus Tchudinov, 1983
Type species
†Ivantosaurus ensifer Tchudinov, 1983

Ivantosaurus is an extinct genus of therapsid that lived in Russia during the Wordian stage of the Permian period, named in honor of Ivan Antonovich Efremov (the great Soviet paleontologist).

Description

Life restoration

Ivantosaurus is based on a very fragmentary skull, consisting of 2 partial maxillae and a quadrate. The specimen was discovered in the Perm Region of the Ochersky District, Russia. Fossils from the region date to the Upper Kazanian Substage of the Upper Permian, making it one of the latest Therapsids known. It was carnivorous and may have grown to a length of 6 meters, approx. Ivantosaurus would have been the largest carnivorous therapsid known, exceeding in size even the largest Late Wordian/early Capitanian anteosaurs.

Teeth

Two canine teeth are set side-to-side in Ivantosaurus' jaw and with their axes inclined forward. It is possible that this therapsid had a unique dentition (no other known animal has two sets of canine teeth), but more likely that a replacement tooth was growing in next to the old tooth about to be lost. Sigogneau-Russell (1989) seems to think this is unlikely, which would make this a quite different animal from Eotitanosuchus. As with the therocephalian family Lycosuchidae, these may simply be replacement canines. There are few known animals, living or extinct, with two sets of canines (it would be a very inefficient chewing mechanism).

See also

• List of therapsids

Sources

• The Age of Dinosaurs in Russia and Mongolia. Benton, Michael J.; Shishkin, Mikhail A.; Unwin, David M. 2003. pp. 91–92.

External links

• Eotitanosuchidae at Kheper
• Therapsida: Biarmosuchia: Biarmosuchidae / Eotitanosuchidae at Palaeos