''Intasuchus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of small to giant tetrapods—often considered Labyrinthodontia, primitive amphi ...

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

from the

Middle Permian The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 ± 0. ...

of Russia. It is known from a single species, ''Intasuchus silvicola'', which was named in 1956. ''Intasuchus'' belongs to the family Intasuchidae and is probably its sole member, although other taxa such as ''

Syndyodosuchus ''Syndyodosuchus'' is an extinct genus of temnospondyl within the family (biology), family Actinodontidae. It is known from the Permian Inta Formation of European Russia. See also * Prehistoric amphibian * List of prehistoric amphibians Referen ...

'' and ''

Cheliderpeton ''Cheliderpeton'' (often misspelled ''Chelyderpeton'') is an extinct genus of temnospondyl amphibian. It lived during the Early Permian in what is now Europe. Fossils have been found from the Ruprechtice horizon of the Intrasudetic Basin of Bohem ...

'' have been assigned to the family in the past. ''Intasuchus'' most likely belongs to the group

Archegosauroidea Archegosauroidea is an extinct superfamily of Permian temnospondyls. The superfamily is assigned to the clade Stereospondylomorpha and is the sister taxon to the suborder Stereospondyli. It includes the families Actinodontidae and Archegosauridae ...

, Permian relatives of the large, mostly Mesozoic temnospondyl clade

Stereospondyli The Stereospondyli are a group of extinct temnospondyl amphibians that existed primarily during the Mesozoic period. They are known from all seven continents and were common components of many Triassic ecosystems, likely filling a similar ecologi ...

Description

''Intasuchus'' has a long, flattened skull that narrows slightly toward the front. Prominent ridges run along the skull surface from the eye sockets to the nostril openings. The

otic notch Otic notches are invaginations in the posterior margin of the skull roof, one behind each orbit. Otic notches are one of the features lost in the evolution of amniotes from their tetrapod ancestors. The notches have been interpreted as part of an ...

at the back of the skull is relatively narrow in comparison to other temnospondyls, although it extends as a groove along the sides of the

skull table The skull roof, or the roofing bones of the skull, are a set of bones covering the brain, eyes and nostrils in bony fishes and all land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparati ...

. ''Intasuchus'' has large teeth on the roof of its mouth, with a large row between two openings of the

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sepa ...

called

choana The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the throat in tetrapods, including humans and other mammals (as well as crocodilia ...

e, tusks on the

palatine bone In anatomy, the palatine bones () are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard palate. (''Palate'' is derived from the Latin ''pa ...

s, and small teeth extending along the ectopterygoid.

Classification

The

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis of Schoch and Milner (2000) placed ''Intasuchus'' as a basal member of a group called

Archegosauriformes Stereospondylomorpha is a clade of temnospondyls. It includes the superfamily Archegosauroidea and the more diverse group Stereospondyli. Stereospondylomorpha was first proposed by Yates and Warren (2000), who found Archegosauroidea and Stereos ...

. It was placed among archegosauroids, although Archegosauroidea was found to be a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

assemblage of taxa basal to Stereospondyli. ''Intasuchus silvicola'' was recovered as the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

of ''Cheliderpeton latirostre'' (now known as '' Glanochthon latirostre''). Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

from that analysis:

References

Permian temnospondyls Fossils of Russia Fossil taxa described in 1956 Prehistoric amphibian genera {{temnospondyli-stub