''Shansisuchus'' (meaning "Shansi Province crocodile") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of archosauriform reptile belonging to the family

Erythrosuchidae Erythrosuchidae (meaning "red crocodiles" in Greek) are a family of large basal archosauriform carnivores that lived from the later Early Triassic (Olenekian) to the early Middle Triassic (Anisian). Naming The family Erythrosuchidae was named by ...

that lived during the

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 in chronostratigraphy. The Middle Triassic spans the time between Ma and ...

in what is now China. The first fossils of ''Shansisuchus'' were discovered from the

Ermaying Formation The Ermaying Formation is a sedimentary succession of Anisian (Middle Triassic) age. It is found in the Shaanxi Province of China. It is composed of an up to 600 m thick sequence of mudstone and sandstone. It is famous for its fossils of tetrapods. ...

of Shansi Province in 1964 by Chinese paleontologist

Yang Zhongjian Yang Zhongjian, also Yang Chung-chien (; 1 June 1897 – 15 January 1979), courtesy name Keqiang (), also known as C.C. (Chung Chien) Young, was a Chinese paleontologist and zoologist. He was one of China's foremost vertebrate paleontologists. H ...

. Like other erythrosuchids, ''Shansisuchus'' was a large-bodied carnivore with a large, deep skull. ''Shansisuchus'' is unique among early archosauriforms in having a hole in its skull called a subnarial fenestra.

Description

''Shansisuchus'' is a large erythrosuchid distinguished from other members of the group by two characters: a tongue-and-groove articulation between the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

and nasal bones of the skull and the presence of a subnarial fenestra. In ''Shansisuchus'' the premaxilla, a bone that makes up the front of the snout, projects backward and fits into a groove in the nasal, a bone that makes up the top of the snout. The subnarial fenestra is present between the external nares (nasal opening) and the

antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, bird ...

, a hole in front of the eye socket. It is separated from the antorbital fenestra by a vertical projection of 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. T ...

bone. A subnarial fenestra is present in a few other more derived archosauriforms such as some

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s and

pseudosuchian Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...

s, but its morphology in ''Shansisuchus'' is unique.

History of research

''Shansisuchus'' is known from many fossil skeletons representing more than a dozen individuals, making it one of the best known erythrosuchids. However, all but one specimen discovered in 2010 (a complete skull and 14 vertebrae from

Jixian County Jixian County () is a county of eastern Heilongjiang province, People's Republic of China. It is under the jurisdiction of the prefecture-level city of Shuangyashan. Administrative divisions Jixian County is divided into 5 towns and 3 townships ...

) are disarticulated, meaning that many aspects of its anatomy had been poorly understood before that specimen was described. Most specimens have been found in a fossil locality in Wuxiang County, and others have been found in localities in Ningwu, Yushe,

Jingle A jingle is a short song or tune used in advertising and for other commercial uses. Jingles are a form of sound branding. A jingle contains one or more hooks and meaning that explicitly promote the product or service being advertised, usually ...

, and

Xing XING is a Hamburg-based career-oriented social networking site, operated by New Work SE (until mid-2019 ''XING SE''). The site is primarily focused on the German-speaking market, alongside XING Spain, and competes with the American platform Li ...

counties. Three species of ''Shansisuchus'' have been named: 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 specime ...

''Shansisuchus shansisuchus'', which is known from over ten individuals; ''S. heiyuekouensis'', which is known from five individuals; and ''S. kuyeheensis'', which is known from one individual.

Relationships

''Shansisuchus'' belongs to a group of reptiles called

Archosauriformes Archosauriformes (Greek for 'ruling lizards', and Latin for 'form') is a clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Latest Permian (roughly 252 million years ago). It was defined by Jacques Gauthier ...

, which is today represented by crocodilians and birds but also includes a diversity of extinct forms extending back to the

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

. It is a basal archosauriform that lies outside Archosauria, the crown group originating with the

last common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...

of birds and crocodilians. When ''Shansisuchus'' was first described, Yang placed it in its own family, Shansisuchidae. In 1992 ''Shansisuchus'' was reassigned to the family Erythrosuchidae and proposed to be the closest relative of the genus ''

Vjushkovia ''Garjainia'' is an extinct genus of erythrosuchid archosauriform reptile from the Olenekian of Russia and South Africa. It was approximately 1.50–2 m (5–6 ft 8 in) long. It contained two species, ''Garjainia prima'' from the Yarengian/ ...

'' (now considered a synonym of''Garjainia''). A

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis published in 2013 found that ''Vjushkovia'' was more closely related to ''Erythrosuchus'', and that ''Shansisuchus'' lied outside the ''Vjushkovia''+''Erythrosuchus'' clade as a more basal erythrosuchid. Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from the 2013 analysis:

References

External links

Shansisuchus on the Paleobiology Database
{{Taxonbar, from=Q1008362 Erythrosuchids Prehistoric reptile genera Middle Triassic reptiles of Asia Triassic China Fossils of China Fossil taxa described in 1964 Taxa named by Yang Zhongjian