Erpetosuchus
Encyclopedia
Erpetosuchus is an extinct genus
of crurotarsan
from the Late Triassic
. It was first described by E. T. Newton in 1894 for remains found in northeastern Scotland
, with more remains found in the United States
in recent years. Erpetosuchus is the sister-taxon to Crocodylomorpha
.
The type species
of Erpetosuchus is E. granti.
in Scotland (late Carnian, Late Triassic), and consist of a skull and a partial postcranial skeleton. The holotype
is BMNH R3139
During a field trip in 1995 to the lower part of the New Haven Formation in Connecticut
, American palaeontologist Paul E. Olsen
discovered a partial skull that, after preparation and description in 2000 (Olsen et al. 2000), was referable to E. granti. This was the first record of E. granti outside of 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 (Late Triassic) age.
n.
A more recent phylogenetic analysis by Olsen et al. (2000) found E. granti to be the sister-taxon to the Crocodylomorpha. These are united in a clade by the following synapomorphies:
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...
of crurotarsan
Crurotarsi
The Crurotarsi are a group of archosauriformes, represented today by the crocodiles,...
from the Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
. It was first described by E. T. Newton in 1894 for remains found in northeastern Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, with more remains found in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in recent years. Erpetosuchus is the sister-taxon to Crocodylomorpha
Crocodylomorpha
The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were...
.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of Erpetosuchus is E. granti.
Material
The first remains of Erpetosuchus were found in the Lossie Mouth Sandstone FormationLossie Mouth Sandstone Formation
The Lossie Mouth Sandstone Formation is a geological formation in Scotland. It dates back to the late Carnian.-Vertebrate fauna:...
in Scotland (late Carnian, Late Triassic), and consist of a skull and a partial postcranial skeleton. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
is BMNH R3139
During a field trip in 1995 to the lower part of the New Haven Formation in Connecticut
Connecticut
Connecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...
, American palaeontologist Paul E. Olsen
Paul E. Olsen
Paul E. Olsen 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 National Natural Landmark as a teenager by sending President Richard Nixon a...
discovered a partial skull that, after preparation and description in 2000 (Olsen et al. 2000), was referable to E. granti. This was the first record of E. granti outside of 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 (Late Triassic) age.
Systematics
Erpetosuchus granti was originally assigned to Thecodontia, but that name no longer appears in scientific literature because it is a paraphyletic group, consisting of distantly related archosaurs. It has also been considered a crocodylomorph, included within the clade Erpetosuchia, or as a pseudosuchiaPseudosuchia
Pseudosuchia is the name originally given to a group of prehistoric reptiles from the Triassic period. The name has been variously interpreted, and it is still sometimes, if infrequently, used in scientific literature today. A more commonly used name, Crurotarsi, is often substituted for...
n.
A more recent phylogenetic analysis by Olsen et al. (2000) found E. granti to be the sister-taxon to the Crocodylomorpha. These are united in a clade by the following synapomorphies:
- Medial contact of the maxillae to form a secondary bony palate
- Absence of a postfrontal
- Parietals fused without a trace of an interparietal suture