Phthinosuchia is an extinct group of therapsids including two poorly known species, Phthinosuchus discors and Phthinosaurus borrisiaki, from the Middle Permian of Russia. Phthinthosuchus is known a partial crushed skull and Phthinosaurus is known from an isolated lower jaw.[1] The two species have traditionally been grouped together based on their shared primitive characteristics, but more recent studies have proposed that they are more distantly related. Phthinosuchus is either a carnivorous gorgonopsian relative[2] or an anteosaurian dinocephalian while Phthinosaurus is either a herbivorous rhopalodont dinocephalian[2][3] or a therocephalian.[4]
| Phthinosuchia Temporal range: Middle Permian, | |
|---|---|
 | |
| Life restoration of Phthinosuchus discors | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Therapsida |
| Suborder: | †Dinocephalia (?) |
| Clade: | †Anteosauria (?) |
| Infraorder: | †Phthinosuchia Romer, 1961 |
| Subgroups | |
See text. | |
Phthinosuchia was named by American paleontologist Everett C. Olson in 1961, who considered it the most primitive infraorder within Therapsida. A year later Olson named the new infraorder Eotheriodontia and reclassified Phthinosuchia as a subgroup of eotheriodonts, along with the families Biarmosuchidae and Brithopodidae. Each species has been placed in its own family; Phthinosuchidae was named by Soviet paleontologist Ivan Yefremov in 1954 for both Phthinthosuchus and Phthinosaurus, while Phthinosauridae was named by Leonid Tatarinov in 1974 for Phthinosaurus alone.[5]