Phthinosuchia is an extinct group of therapsids including two poorly known species, ''

Phthinosuchus discors ''Phthinosuchus'' is an extinct genus of therapsids from the Middle Permian of Russia. ''Phthinosuchus'' is the sole member of the family Phthinosuchidae. ''Phthinosuchus'' may have been one of the most primitive therapsids, meaning that its ance ...

'' and ''

Phthinosaurus borrisiaki ''Phthinosaurus'' is an extinct genus of therapsids from the Middle Permian of Russia. The type species ''Phthinosaurus borrisiaki'' was named by Soviet paleontologist Ivan Yefremov in 1940 on the basis of an isolated lower jaw. Because this jaw ...

'', from the Middle Permian of Russia. ''Phthinthosuchus'' is known a partial crushed skull and ''Phthinosaurus'' is known from an isolated lower jaw. 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 or an anteosaurian dinocephalian while ''Phthinosaurus'' is either a herbivorous rhopalodont dinocephalian or a therocephalian. Phthinosuchia was named by American paleontologist

Everett C. Olson Everett Claire Olson (November 6, 1910 – November 27, 1993) was an American zoologist, paleontologist, and geologist noted for his seminal research of origin and evolution of vertebrate animals. Through his research studying terrestrial verte ...

in 1961, who considered it the most primitive infraorder within Therapsida. A year later Olson named the new infraorder

Eotheriodontia Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...

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 ''Phthinosuchus'' is an extinct genus of therapsids from the Middle Permian of Russia. ''Phthinosuchus'' is the sole member of the family Phthinosuchidae. ''Phthinosuchus'' may have been one of the most primitive therapsids, meaning that its ance ...

was named by Soviet paleontologist Ivan Yefremov in 1954 for both ''Phthinthosuchus'' and ''Phthinosaurus'', while Phthinosauridae was named by

Leonid Tatarinov Leonid (russian: Леонид ; uk, Леонід ; be, Леанід, Ljeaníd ) is a Slavic version of the given name Leonidas. The French version is Leonide. People with the name include: * Leonid Andreyev (1871–1919), Russian playwright a ...

in 1974 for ''Phthinosaurus'' alone.

References

Prehistoric therapsids Permian synapsids {{paleo-Therapsid-stub