''Silphedosuchus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

therocephalia Therocephalia is an extinct clade of therapsids (mammals and their close extinct relatives) from the Permian and Triassic periods. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their te ...

n therapsids 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 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

. It is a member of the family

Ericiolacertidae Ericiolacertidae is a family of therocephalian therapsids. The family living in the earliest Triassic after the Permian-Triassic extinction event. Genera are: ''Ericiolacerta'' found in the Fremouw Formation of Antarctica and the Normandien For ...

, along with the genus ''

Ericiolacerta ''Ericiolacerta'' is an extinct genus of small therocephalian therapsids from the early Triassic of South Africa and Antarctica. ''Ericiolacerta,'' meaning "hedgehog lizard" (from the Latin ''ericius'', "hedgehon" and ''lacerta'', "lizard"), wa ...

'' from

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

and

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

''Silphedosuchus orenburgensis'' was described in 1977 on the basis of a single

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

skull from

Orenburg Oblast Orenburg Oblast (also Orenburzhye) is a federal subject of Russia (an oblast), mainly located in Eastern Europe. Its administrative center is the city of Orenburg. From 1938 to 1957, it bore the name Chkalov Oblast in honor of Valery Chkal ...

. ''Silphedosuchus'' was found in the Rassypnaya locality of Orenburg Oblast, dating back to the

Olenekian In the geologic timescale, the Olenekian is an age (geology), age in the Early Triassic epoch (geology), epoch; in chronostratigraphy, it is a stage (stratigraphy), stage in the Lower Triassic series (stratigraphy), series. It spans the time betw ...

stage of the Early Triassic. It was found in a fine-grained

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

that contains few other vertebrates. This layer was deposited in a large floodplain that covered much of European Russia during the Early Triassic. At the Rassypnaya locality, a

lens A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...

of coarser sand, presumably deposited by an ancient river, cuts through the finer-grained sandstone. This deposit contains many tetrapods such as

temnospondyls Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished wo ...

and

archosauromorph Archosauromorpha (Greek for "ruling lizard forms") is a clade of diapsid reptiles containing all reptiles more closely related to archosaurs (such as crocodilians and dinosaurs, including birds) than to lepidosaurs (such as tuataras, lizards, a ...

s, but the fossils are part of a different faunal assemblage. The skull is about in length, with a long and pointed snout. ''Silphedosuchus'' lacks the large canine teeth present in most other therocephalians, and has rounded crushing teeth at the back of the jaws with several cusps. ''Silphedosuchus'' has large

orbits In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...

or eye sockets with raised edges. The eye socket is not entirely closed because the postorbital process, which forms the posterior margin of the orbit, does not reach the

jugal bone The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic bone, zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by spe ...

below, which forms the bottom margin of the orbit. Characters that distinguish ''Silphedosuchus'' from ''Ericiolacerta'' include a narrow contact between the

palatine A palatine or palatinus (Latin; : ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman Empire, Roman times.

and

vomer The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms ...

bones on the roof of the mouth, a contact between the vomer and the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

which is positioned further forward, and very wide buccal or cheek teeth.

References

Extinct animals of Russia Baurioidea Therocephalia genera Triassic synapsids Fossil taxa described in 1977 Taxa named by Leonid Petrovich Tatarinov {{paleo-therapsid-stub