''Benthosuchus'' (meaning "deep water crocodile") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

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

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. It was primarily aquatic, living in rivers and lakes. Multiple species are known, with the largest reaching about 2.5 meters in length. Russian paleontologist Ivan Yefremov fremovcalled the genus ''Benthosaurus'' "deep water lizard" (from Ancient Greek βένθος (''benthos'') "depth, deep water") in his original 1929 description, "in view of its clearly indicated adaptation to life in deep water" shown by "the position of the orbits and the flatness of the skull." The type species ''B. sushkini'' honored his late teacher Petr Sushkin. The generic name was preoccupied by ''Benthosaurus'' Goode & Bean, 1886, a fish, and he renamed the genus ''Benthosuchus'' ("deep water crocodile") in 1937.Efremov, I. A. (1929). ''Benthosaurus sushkini'', ein neuer Labyrinthodont der permotriassischen Ablagerungen der Sharschenga Flusses. ''Bulletin of the Academy of Sciences of the USSR'' 8:747-770. nglish translation: https://paleoglot.org/files/Efremov%201929b.pdf/ref>Efremov, I.A. (1937). On the Stratification of Continental Permian and Triassic the Soviet Union Based on the Terrestrial Vertebrate Fauna. ''Doklady Akademii Nauk SSSR. Nov. Ser. 16(2)'': 125–132. ''Benthosuchus'' has traditionally been considered a member of the temnospondyl superfamily Trematosauroidea, and the family Benthosuchidae was established in 1940 to include ''Benthosuchus'' and the related trematosauroid ''

Thoosuchus ''Thoosuchus'' (meaning "active crocodile") is an extinct genus of basal trematosauroid trematosaurian temnospondyl. Fossils have been found from Russia and date back to the Early Triassic. It is the type genus of the family Thoosuchidae, for ...

''. Some recent

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 ...

studies have removed ''Benthosuchus'' from Trematosauroidea entirely, placing it as a closer relative of

Mastodonsauroidea The Mastodonsauroidea are an extinct superfamily of temnospondyl amphibians known from the Triassic. Fossils belonging to this superfamily have been found in North America, Greenland, Europe, Asia, and Australia. The genus '' Ferganobatrachus'' ...

, another group of Triassic temnospondyls. Other studies retain ''Benthosuchus'' within Trematosauroidea, but since ''Benthosuchus'' and ''Thoosuchus'' have successively basal positions on these trees they form 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 ...

grouping, not a valid clade. In either case, Benthosuchidae is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

family containing only ''Benthosuchus''.

Description

''Benthosuchus''

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

is about 0.75 m long (it is comparatively short in young individuals but lengthens with age), and the overall body length is about 2.5 m. It existed in widely overflowing rivers of the

East Russian Depression East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fac ...

Phylogeny

''Benthosuchus'' is traditionally considered a close relative of a group of temnospondyls called

capitosaurid Mastodonsauridae is a family of capitosauroid temnospondyls. Fossils belonging to this family have been found in North America, Greenland, Europe, Asia, and Australia. The family Capitosauridae is synonymous with Mastodonsauridae. Description S ...

s. In particular, it bears a close resemblance to the capitosaurid ''

Wetlugasaurus ''Wetlugasaurus'' (meaning "Vetluga River lizard") is an extinct genus of Temnospondyli, temnospondyl amphibian from the Early Triassic (Olenekian) Charkabozh Formation, Charkabozh, Kzylsaiskaya Formation, Kzylsaiskaya, Petropavlovka Formation, ...

''. Many of the early large-scale phylogenetic analyses of temnospondyls place ''Benthosuchus'' within a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

called

Capitosauria Capitosauria is an extinct group of large temnospondyl amphibians with simplified stereospondyl vertebrae. Mainly living as piscivores in lakes and rivers, the Capitosauria and its sister taxon Trematosauria were the only major labyrinthodonts t ...

. However, more recent analyses such as that of Fortuny ''et al.'' (2011) recover ''Benthosuchus'' within another clade called

Trematosauria Trematosauria is one of two major groups of temnospondyl amphibians that survived the Permian-Triassic extinction event, the other (according to Yates and Warren 2000) being the Capitosauria. The trematosaurs were a diverse and important group th ...

. Occasionally it is grouped near the trematosaurid family

Trematosauridae Trematosauridae are a family of large marine temnospondyl amphibians with many members. They first appeared during the Induan age of the Early Triassic, and existed until around the Carnian stage of the Late Triassic, although by then they wer ...

as a basal member of the group Trematosauroidea. Fortuny ''et al.'' found that ''Benthosuchus'' positioned outside Trematosauroidea as a more basal trematosaurian. Below is a cladogram from Fortuny ''et al.'' (2011) showing the

placement of ''Benthosuchus'':

References

{{Taxonbar, from=Q2395740 Trematosaurs Triassic temnospondyls Extinct animals of Russia Fossil taxa described in 1937 Taxa named by Ivan Yefremov