Plinthogomphodon
Encyclopedia
Plinthogomphodon is a genus
of traversodontid cynodont
from the Late Triassic
of the eastern United States
. Fossils have been found from the Deep River basin
of North Carolina
, part of the larger Newark Supergroup. It is known from a single eroded snout. The type
and only species is P. herpetairus.
, as it was found in mudstone
used to make bricks and its postcanine teeth resemble molar
s. The type species is P. herpetairus, meaing "companion of reptiles" from the Greek herpeton ("reptile") and hetairos ("companion"). The name alludes to the close proximity of the holotype specimen to the remains of a rauisuchia
n and a sphenosuchia
n archosaur
when it was first discovered.
The holotype only preserves the underside of the snout, as the dorsal surface has eroded away. The tip of the snout is broad, but it constricts behind the canines. The tips of most teeth are also worn away, except for two postcanine teeth that had not yet erupted and were exposed during the fossil's preparation for study. Because the teeth had not yet emerged, the individual was probably a juvenile. Like most traversodotids, Plinthogomphodon has a pair of large canine teeth and several wide, cusped postcanine teeth. The postcanines of Plinthogomphodon are much wider than they are long and closely packed together. Based on the postcanine that had not erupted in the holotype, the postcanine of Plinthogomphodon has three main cusps: a lingual cusp near the mouth, a slightly smaller central cusp, and a relatively large buccal cusp near the cheek. There are also smaller accessory cusps in front of the buccal cusp.
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 traversodontid cynodont
Cynodont
Cynodontia or cynodonts are a taxon of therapsids which first appeared in the Late Permian and were eventually distributed throughout all seven continents by the Early Triassic . This clade includes modern mammals and their extinct close relatives. They were one of the most diverse groups of...
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...
of the eastern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Fossils have been found from the Deep River basin
Deep River (North Carolina)
The Deep River is a tributary of the Cape Fear River, approximately 125 miles long, in north central North Carolina in the United States.- Course :...
of North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
, part of the larger Newark Supergroup. It is known from a single eroded snout. The type
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...
and only species is P. herpetairus.
Description and history
Plinthogomphodon was named in 1999. The name means "brick molar tooth" in GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
, as it was found in mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
used to make bricks and its postcanine teeth resemble molar
Molar
Molar may refer to:*Molar , the fourth kind of tooth in mammals*Molar , another name for the Spanish wine grape Listan Negro*Molar concentration, a unit of concentration, or molarity, of solutions equal to 1 mole per litre*Molar volume...
s. The type species is P. herpetairus, meaing "companion of reptiles" from the Greek herpeton ("reptile") and hetairos ("companion"). The name alludes to the close proximity of the holotype specimen to the remains of a rauisuchia
Rauisuchia
Rauisuchia is a group of predatory and mostly large Triassic archosaurs. As a clade, Rauisuchia includes these Triassic forms and all crocodylomorphs, which are descendants of Triassic rauisuchians. The group in its traditional sense is paraphyletic, because it does not include crocodylomorph...
n and a sphenosuchia
Sphenosuchia
Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Late Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, which include all living crocodilians.-Stratigraphic...
n archosaur
Archosaur
Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...
when it was first discovered.
The holotype only preserves the underside of the snout, as the dorsal surface has eroded away. The tip of the snout is broad, but it constricts behind the canines. The tips of most teeth are also worn away, except for two postcanine teeth that had not yet erupted and were exposed during the fossil's preparation for study. Because the teeth had not yet emerged, the individual was probably a juvenile. Like most traversodotids, Plinthogomphodon has a pair of large canine teeth and several wide, cusped postcanine teeth. The postcanines of Plinthogomphodon are much wider than they are long and closely packed together. Based on the postcanine that had not erupted in the holotype, the postcanine of Plinthogomphodon has three main cusps: a lingual cusp near the mouth, a slightly smaller central cusp, and a relatively large buccal cusp near the cheek. There are also smaller accessory cusps in front of the buccal cusp.