Benthosuchus

Benthosuchus is an extinct genus of temnospondyl amphibian from the Early Triassic of Russia. The genus was named in 1937, and the type species, "Benthosuchus sushkini", was named in 1940. "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". Some recent phylogenetic studies have removed "Benthosuchus" from Trematosauroidea entirely, placing it as a closer relative of Mastodonsauroidea, 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 grouping, not a valid clade. In either case, Benthosuchidae is a monotypic family containing only "Benthosuchus".
Description.
"Benthosuchus" skull 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.
Phylogeny.
"Benthosuchus" is traditionally considered a close relative of a group of temnospondyls called capitosaurids. In particular, it bears a close resemblance to the capitosaurid "Wetlugasaurus". Many of the early large-scale phylogenetic analyses of temnospondyls place "Benthosuchus" within a clade called Capitosauria. However, more recent analyses such as that of Fortuny "et al." (2011) recover "Benthosuchus" within another clade called Trematosauria. Occasionally it is grouped near the trematosaurid family Trematosauridae 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 phylogenetic placement of "Benthosuchus":