Erythrosuchus
Encyclopedia
Erythrosuchus is an extinct genus of archosauriform reptile
from the Triassic
of South Africa
and Namibia
. Remains have been found from the Cynognathus Assemblage Zone
of the Beaufort Group
in the Karoo
of South Africa as well as the Omingonde Formation in Namibia.
Erythrosuchus was the largest predator of its time, at around 5 metres (16.4 ft) long, and 2.1 metres (6.9 ft) tall. It walked on all fours and had limbs which were positioned semi-vertically under its body, unlike the more sprawling gait of most earlier reptiles. Its head was huge and dinosaur
-like, reaching a length of 1 metres (3.3 ft), and had sharp, conical teeth.
In the Late Triassic
, the ecological niche
left by Erythrosuchus was filled by creatures like Saurosuchus
and Postosuchus
.
, a bone at the rear of the skull. In other erythrosuchids, the margin of this bone projects backward from the skull, giving it a hook-like appearance. In Erythrosuchus, the margin is convex and lacks a hook.
Erythrosuchus is known from many specimens, most of which are fragmentary. The holotype
, described by Robert Broom
in 1905 and known as SAM
905, is poorly preserved. Only small pieces of the limbs, pectoral and pelvic girdles, skull, and a few vertebrae present in this specimen. A thorough description of the genus was given by German
paleontologist Friedrich von Huene
in 1911. The fossil material that served as the basis for the description is now housed in the Natural History Museum
in London
, England
. Like the holotype, it is very fragmentary, and some specimens may even belong to the same individual as SAM 905. One specimen, known as BMNH
R 3592, is relatively more complete, with much of the postcranial skeleton
intact.
Early restorations of the skull of Erythrosuchus depicted it as being tall, similar in appearance to Tyrannosaurus
. However, a complete skull that was later described in 1963 revealed that the true shape was less tall than previously thought. This skull, known as BPI
5207 and currently part of the collection of the Bernard Price Institute for Palaeontological Research
in South Africa, has a somewhat pointed snout. Earlier restorations may have shown a deeper snout because it was not known at the time how the bones of the skull articulated with one another.
The braincase has also been studied, and possesses features that are shared with other early archosauriforms. Many of these characteristics are considered plesiomorphic, or ancestral, in archosaur
s. While Erythrosuchus is not considered an archosaur, it is thought to be closely related to the last common ancestor of all archosaurs.
The hypothetical last common ancestor of archosaurs is thought to have shared many features with Erythrosuchus, many of which are found in the braincase. For example, the inner part of the otic capsule (the skeletal structure surrounding the inner ear
) is not entirely ossified, or completely formed of bone. Neither is the channel for the perilymphatic duct
, which is a tube that leaves the lagena. The lagena is the portion of the inner ear responsible for hearing, and is known as the cochlea
in mammals (although in mammals it is coiled rather than straight). Erythrosuchus has a short lagena, which is also expected in the last common ancestor of all archosaurs.
Some features of the ankle of Erythrosuchus suggest that it was beginning to adapt toward digitigrady
, or walking on toes rather than having the entire foot placed on the ground. The ankle is similar to that of Euparkeria
; the ankles of both of these animals are more advanced than those of other archosauriformes.
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
from the Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
of South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
and Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
. Remains have been found from the Cynognathus Assemblage Zone
Cynognathus Assemblage Zone
The Cynognathus Assemblage Zone is a geological stratum and a faunal zone of the Beaufort Group, of the South African Karoo. The name refers to Cynognathus, a genus of eucynodontian mammal-like reptile, whose fossils have been found in that structure....
of the Beaufort Group
Beaufort Group
The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup of geological strata in Southern Africa. It follows conformably after the Ecca Group and consists essentially of sandstones and shales, deposited in the Karoo Basin from the Middle Permian to the early part of the...
in the Karoo
Karoo
The Karoo is a semi-desert region of South Africa. It has two main sub-regions - the Great Karoo in the north and the Little Karoo in the south. The 'High' Karoo is one of the distinct physiographic provinces of the larger South African Platform division.-Great Karoo:The Great Karoo has an area of...
of South Africa as well as the Omingonde Formation in Namibia.
Erythrosuchus was the largest predator of its time, at around 5 metres (16.4 ft) long, and 2.1 metres (6.9 ft) tall. It walked on all fours and had limbs which were positioned semi-vertically under its body, unlike the more sprawling gait of most earlier reptiles. Its head was huge and dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
-like, reaching a length of 1 metres (3.3 ft), and had sharp, conical teeth.
In 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...
, the ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
left by Erythrosuchus was filled by creatures like Saurosuchus
Saurosuchus
Saurosuchus is an extinct genus of rauisuchian archosaur in the family Prestosuchidae. With a length of around 7 m , it was the largest rauisuchian, except perhaps for the less well known Fasolasuchus. Like other rauisuchians, Saurosuchus walked on four fully erect limbs...
and Postosuchus
Postosuchus
Postosuchus, meaning "crocodile from Post ", was a basal archosaur that lived in what is now North America during the middle through to the late Triassic period...
.
Description
Erythrosuchus was the largest erythrosuchid, but apart from its size, it was similar in appearance to other related genera. It had a large head and comparatively short neck. One of the only distinguishing features of Erythrosuchus other than its size is the smoothness of the margin of the squamosalSquamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
, a bone at the rear of the skull. In other erythrosuchids, the margin of this bone projects backward from the skull, giving it a hook-like appearance. In Erythrosuchus, the margin is convex and lacks a hook.
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...
, described by Robert Broom
Robert Broom
Professor Robert Broom was a Scottish South African doctor and paleontologist. He qualified as a medical practitioner in 1895 and received his DSc in 1905 from the University of Glasgow...
in 1905 and known as SAM
Iziko South African Museum
The Iziko SA Museum is a South African national museum located in Cape Town. The museum was founded in 1825, the first in the country. It has been on its present site in the Company's Garden since 1897...
905, is poorly preserved. Only small pieces of the limbs, pectoral and pelvic girdles, skull, and a few vertebrae present in this specimen. A thorough description of the genus was given by German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
paleontologist Friedrich von Huene
Friedrich von Huene
Friedrich von Huene was a German paleontologist who named more dinosaurs in the early 20th century than anyone else in Europe.-Biography:...
in 1911. The fossil material that served as the basis for the description is now housed in the Natural History Museum
Natural History Museum
The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. Like the holotype, it is very fragmentary, and some specimens may even belong to the same individual as SAM 905. One specimen, known as BMNH
Natural History Museum
The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
R 3592, is relatively more complete, with much of the postcranial skeleton
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
intact.
Early restorations of the skull of Erythrosuchus depicted it as being tall, similar in appearance to Tyrannosaurus
Tyrannosaurus
Tyrannosaurus meaning "tyrant," and sauros meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex , commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other...
. However, a complete skull that was later described in 1963 revealed that the true shape was less tall than previously thought. This skull, known as BPI
Bernard Price Institute for Palaeontological Research
The Bernard Price Institute for Palaeontological Research is part of the School of Geosciences in the Faculty of Science of the University of the Witwatersrand, Johannesburg, South Africa...
5207 and currently part of the collection of the Bernard Price Institute for Palaeontological Research
Bernard Price Institute for Palaeontological Research
The Bernard Price Institute for Palaeontological Research is part of the School of Geosciences in the Faculty of Science of the University of the Witwatersrand, Johannesburg, South Africa...
in South Africa, has a somewhat pointed snout. Earlier restorations may have shown a deeper snout because it was not known at the time how the bones of the skull articulated with one another.
The braincase has also been studied, and possesses features that are shared with other early archosauriforms. Many of these characteristics are considered plesiomorphic, or ancestral, in 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...
s. While Erythrosuchus is not considered an archosaur, it is thought to be closely related to the last common ancestor of all archosaurs.
The hypothetical last common ancestor of archosaurs is thought to have shared many features with Erythrosuchus, many of which are found in the braincase. For example, the inner part of the otic capsule (the skeletal structure surrounding the inner ear
Inner ear
The inner ear is the innermost part of the vertebrate ear. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:...
) is not entirely ossified, or completely formed of bone. Neither is the channel for the perilymphatic duct
Perilymphatic duct
The perilymphatic duct is where the perlyphatic space is connected to the subarachnoid space. This works as a type of shunt to eliminate excess perilymph fluid from the perlymphatic space around the cochlea of the ear. Perilymph is continuous with cerebrospinal fluid in the subarachnoid space...
, which is a tube that leaves the lagena. The lagena is the portion of the inner ear responsible for hearing, and is known as the cochlea
Cochlea
The cochlea is the auditory portion of the inner ear. It is a spiral-shaped cavity in the bony labyrinth, making 2.5 turns around its axis, the modiolus....
in mammals (although in mammals it is coiled rather than straight). Erythrosuchus has a short lagena, which is also expected in the last common ancestor of all archosaurs.
Some features of the ankle of Erythrosuchus suggest that it was beginning to adapt toward digitigrady
Digitigrade
A digitigrade is an animal that stands or walks on its digits, or toes. Digitigrades include walking birds , cats, dogs, and many other mammals, but not plantigrades or unguligrades...
, or walking on toes rather than having the entire foot placed on the ground. The ankle is similar to that of Euparkeria
Euparkeria
Euparkeria was a small African reptile of the early Triassic period between 248-245 million years ago, close to the ancestry of the archosaurs.- Palaeobiology :...
; the ankles of both of these animals are more advanced than those of other archosauriformes.