''Silphedosuchus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...

s 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 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. It is a member of the family Ericiolacertidae, along with the genus ''

Ericiolacerta Left may refer to: Music * ''Left'' (Hope of the States album), 2006 * ''Left'' (Monkey House album), 2016 * "Left", a song by Nickelback from the album ''Curb'', 1996 Direction * Left (direction), the relative direction opposite of right * L ...

'' from

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

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, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

. The

type species In 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 species that contains the biological type specimen ...

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

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

skull from

Orenburg Oblast Orenburg Oblast (russian: Оренбургская область, ''Orenburgskaya oblast'') is a federal subject of Russia (an oblast). Its administrative center is the city of Orenburg. From 1938 to 1957, it bore the name ''Chkalov Oblast'' () ...

. ''Silphedosuchus'' was found in the Rassypnaya locality of Orenburg Oblast, dating back to the Olenekian stage of the Early Triassic. It was found in a fine-grained

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

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 of coarser sand, presumably deposited by an ancient river, cuts through the finer-grained sandstone. This deposit contains many tetrapods such as temnospondyls and archosauromorphs, but the fossils are part of a different faunal assemblage. The skull is about long, 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 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. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy ...

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

vomer The vomer (; lat, vomer, lit=ploughshare) 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 maxill ...

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

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates 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 t ...

that is positioned farther forward, and very wide buccal or cheek teeth.

References

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