Neotrirachodon is an extinct genus of synapsid

Synapsid

Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...

 which existed in Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 during the Middle Triassic

Middle Triassic

In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma...

 period. It contains the species Neotrirachodon expectatus.

It is known from a jaw

Jaw

The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...

 fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 consisting of the left dentary with postcanines. It was recovered from the Donguz Formation, Orenburg Oblast

Orenburg Oblast

Orenburg Oblast is a federal subject of Russia . Its administrative center is the city of Orenburg. From 1938 to 1957, it bore the name Chkalov Oblast in honor of Valery Chkalov...

 of Russia. The fossil was first described as belonging to the genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Antecosuchus

Antecosuchus

Antecosuchus is a genus of therocephalian therapsid.-References:*...

(as Antecosuchus ochevi), a traversodont

Traversodontidae

Traversodontidae is a family of herbivorous cynodonts. Traversodonts were primarily Gondwanan, with many species known from Africa and South America. Recently, traversodonts have also been found from Europe and eastern North America. Traversodonts first appeared in the Middle Triassic, diversified...

.

It has tentatively been classified as a trirachodontid

Trirachodontidae

Trirachodontidae is an extinct family of cynognathian cynodonts from the Triassic of China and southern Africa. Trirachodontids appeared during the Early Triassic soon after the Permian-Triassic extinction event and quickly spread over a wide geographic area in a comparatively brief amount of time...

 gomphodont pending further fossil discoveries. Gomphodonts (or tritylodonts) are herbivorous cynodont

Cynodont

Cynodontia or cynodonts are a taxon of therapsids which first appeared in the Late Permian and were eventually distributed throughout all seven continents by the Early Triassic . This clade includes modern mammals and their extinct close relatives. They were one of the most diverse groups of...

s. If correct, it would be the first trirachodontid described from Russia.

Its classification remains uncertain, however. Other studies treat it as an incertae sedis

Incertae sedis

, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...

gomphodont, while others propose that it's more likely to be a bauriid

Bauriidae

Bauriidae is a family of therocephalian therapsids. Bauriids are among the most advanced eutherocephalians and possess several mammal-like features such as a secondary palate. Unlike other therocephalians, bauriids were herbivorous. Two subfamilies are classified within Bauriidae:...

 therocephalian

Therocephalia

Therocephalians are an extinct suborder of carnivorous eutheriodont therapsids that lived from the middle and late Permian into the Triassic 265.0—245.0 Ma existing for approximately ....

rather than a trirachodontid.