''Ivantosaurus'' is an
extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
therapsid that lived in
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
during the
Wordian
In the geologic timescale, the Wordian is an age or stage of the Permian. It is the middle of three subdivisions of the Guadalupian Epoch or Series. The Wordian lasted between and million years ago (Ma). It was preceded by the Roadian and fo ...
stage of the
Permian
The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...
period, named in honor of paleontologist
Ivan Antonovich Efremov
Ivan Antonovich (Antipovich) Yefremov, sometimes Efremov (; 23 April 1908 – 5 October 1972) was a Soviet paleontologist, science-fiction author and social thinker. He founded taphonomy, the study of fossilization patterns.
Biography
He ...
.
Description
''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 .
''Ivantosaurus'' would have been the largest carnivorous
therapsid known, exceeding in size even the largest Late Wordian/early Capitanian
anteosaur
Anteosaurs are a group of large, primitive carnivorous dinocephalian therapsids with large canines and incisors and short limbs, that are known from the Middle Permian of South Africa, Russia, China, and Brazil. Some grew very large, with skulls ...
s.
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
''Eotitanosuchus'' ("dawn giant crocodile") is an extinct genus of biarmosuchian therapsids whose fossils were found in the town of Ochyor in Perm Krai, Russia. It lived about 267 million years ago. The only species is ''Eotitanosuchus olsoni' ...
''. As with the
therocephalian
Therocephalia is an extinct clade of therapsids (mammals and their close extinct relatives) from the Permian and Triassic periods. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their te ...
family
Lycosuchidae
Lycosuchidae is a Family (biology), family of therocephalians (an extinct type of therapsids, broader group which modern mammals belong to) known from fossils from what is now the Beaufort Group of South Africa and that lived during the Middle Pe ...
, 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).
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See also
* List of therapsids
This list of therapsids is an attempt to create a comprehensive listing of all Genus, genera that have ever been included in the Therapsida excluding mammals and purely vernacular terms. The list includes all commonly accepted genera, but also gene ...
References
Sources
*
External links
Eotitanosuchidae
at Kheper
at Palaeos
{{Taxonbar, from=Q2631004
Biarmosuchia
Prehistoric therapsid genera
Guadalupian synapsids of Europe