''Erpetosuchus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

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 ...

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 ...

from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

. 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 ...

of ''Erpetosuchus'' is ''E. granti''. It was first described by E. T. Newton in 1894 for remains found in northeastern

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

, including four specimens from the latest Carnian Lossiemouth Sandstone Formation. Additional remains of ''Erpetosuchus'' have been found in the

New Haven Formation The New Haven Formation is a geologic formation in Connecticut. It preserves fossils dating back to the Triassic period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entert ...

Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...

in the eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, although they were not attributed to the species ''E. granti''. The relationship of ''Erpetosuchus'' to other archosaurs is uncertain. In 2000 and 2002, it was considered a close relative of the group

Crocodylomorpha Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, cro ...

, which includes living crocodylians and many extinct relatives. However, this relationship was questioned in a 2012 analysis that found the

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 ...

placement of ''Erpetosuchus'' to be very uncertain.

Material

The first remains of ''Erpetosuchus'' were found in the Lossiemouth Sandstone Formation in Scotland, dating back to the late

Carnian The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followed by t ...

stage of the Late Triassic. The

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 ...

specimen is BMNH R3139 and consists of a skull and a partial postcranial skeleton. During a field trip in 1995 to the lower part of the New Haven Formation in

, American

palaeontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

Paul E. Olsen Paul E. Olsen (born August 4, 1953) is an American paleontologist and author and co-author of a large number of technical papers. Growing up as a teenager in Livingston, New Jersey, he was instrumental in Riker Hill Fossil Site being named a Na ...

discovered a partial skull that, after preparation and description in 2000 (Olsen et al. 2000), was referable to ''Erpetosuchus''. This was the first record of ''Erpetosuchus'' outside Scotland. The specimen has been given the number AMNH 29300, and besides the right side of the skull, also has some vertebrae and indeterminate bones associated. Dating of the lower portion of the New Haven Formation indicates a Norian age.

Systematics

''Erpetosuchus granti'' was originally assigned to

Thecodontia Thecodontia (meaning 'socket-teeth'), now considered an obsolete taxonomic grouping, was formerly used to describe a diverse "order" of early archosaurian reptiles that first appeared in the latest Permian period and flourished until the end of t ...

, but that name is no longer considered valid in scientific literature because it is a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

group of early archosaurs. A more recent phylogenetic analysis by Olsen ''et al.'' (2000) found ''E. granti'' to be the sister-taxon to the Crocodylomorpha. These were united in a clade by the following

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

: *Medial contact 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. The t ...

e (upper jaw bones) to form a secondary

bony palate The hard palate is a thin horizontal bony plate made up of two bones of the facial skeleton, located in the roof of the mouth. The bones are the palatine process of the maxilla and the horizontal plate of palatine bone. The hard palate spans ...

*Absence of a

postfrontal The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

bone at the top of the skull *

Parietal bone The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...

s fused without a trace of a suture between them Benton and Walker (2002) found the same sister-group relationship and proposed the name

Bathyotica Bathyotica is a clade of crurotarsan archosaurs that includes the superorder Crocodylomorpha and its sister taxon ''Erpetosuchus'', a small Triassic suchian. Bathyotica was named in a 2002 phylogenetic study of ''Erpetosuchus''. The genus was fo ...

for the clade containing ''Erpetosuchus'' and Crocodylomorpha. Nesbitt and Butler (2012) included ''Erpetosuchus'' within a more comprehensive phylogenetic analysis and found it to group with the archosaur '' Parringtonia'' from the Middle Triassic of Tanzania. Both were part of the clade

Erpetosuchidae Erpetosuchidae is an extinct family of pseudosuchian archosaurs. Erpetosuchidae was named by D. M. S. Watson in 1917 to include ''Erpetosuchus''. It includes the type species '' Erpetosuchus granti'' from the Late Triassic of Scotland, ''Erpetos ...

. Nesbitt and Butler did not find support for the sister-group relationship between ''Erpetosuchus'' and Crocodylomorpha. Instead, erpetosuchids formed a

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...

or unresolved evolutionary relationship at the base of Archosauria along with several other groups. It could take many positions within Archosauria, but none were as a sister taxon of Crocodylomorpha.

References

{{Taxonbar, from=Q840450 Late Triassic pseudosuchians Late Triassic reptiles of Europe Fossil taxa described in 1894 Prehistoric pseudosuchian genera