Erythrosuchidae (meaning "red crocodiles" in

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

) are a family of large basal archosauriform

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

s that lived from the later Early

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

(

Olenekian In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between Ma and Ma (million years ago). The Olenekian is sometimes divided into ...

) to the early Middle Triassic (

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...

Naming

The family Erythrosuchidae was named by

David Meredith Seares Watson Prof David Meredith Seares Watson FRS FGS HFRSE LLD (18 June 1886 – 23 July 1973) was the Jodrell Professor of Zoology and Comparative Anatomy at University College, London from 1921 to 1951. Biography Early life Watson was born in the Highe ...

in 1917.D.M.S. Watson. 1917. "A sketch classification of the Pre-Jurassic tetrapod vertebrates". ''Proceedings of the Zoological Society of London'' 1917: 167–186

Description

They were the

apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...

s of their day, with lengths of to almost . Their fossil remains are known to date from South Africa (

Beaufort Group The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underlie ...

of the

Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hardveld") is a semi-desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its ext ...

Basin), China, India and European Russia, from the Early to

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 ...

. Erythrosuchids were unusually large and robust archosauromorphs. Several features set them apart from other archosauriformes and are also seen in later, more

derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian d ...

s. For example, they lack teeth on the

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sepa ...

, which are found in other early archosauriformes, such as ''

Doswellia ''Doswellia'' is an extinct genus of archosauriform from the Late Triassic of North America. It is the most notable member of the family Doswelliidae, related to the proterochampsids. ''Doswellia'' was a low and heavily built carnivore which liv ...

'' and euparkeriids. In erythrosuchids, the

centra Centra is a convenience shop chain that operates throughout Ireland. The chain operates as a symbol group owned by Musgrave Group, the food wholesaler, meaning the stores are all owned by individual franchisees. The chain has three different ...

(central parts of vertebrae) are deeply indented on either side, differing considerably from the usual cylindrical shape of the centra in early archosauriformes, but similar to later archosaurs. The heads of erythrosuchids are generally disproportionately large and deep. In all erythrosuchids, the lower margin of 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 b ...

, the bone at the tip of the upper jaw, is lower than the lower margin 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 ...

, the bone behind the premaxilla. This forms a characteristic "step" that makes erythrosuchids easily distinguishable from all other early archosauriformes, which have smooth jaw margins that are either straight or gradually curved. Erythrosuchids are notable for being the first archosauriforms to have a triradiate pelvic girdle with three projecting areas formed from three bones: an ilium and an elongated pubis and

ischium The ischium () form ...

. Although it is small, the

fourth trochanter The fourth trochanter is a shared characteristic common to archosaurs. It is a knob-like feature on the posterior-medial side of the middle of the femur shaft that serves as a muscle attachment, mainly for the ''musculus caudofemoralis longus'', ...

, a ridge on the femur that serves as a muscle attachment in archosaurs, first appears in erythrosuchids. The triradiate pelvis and fourth trochanter are both features which indicate that erythrosuchids had an erect stance similar to later archosaurs. More basal archosauriforms such as

proterosuchid Proterosuchidae is an early family of basal archosauriforms whose fossils are known from the Latest Permian and the Early Triassic of Europe, Asia, Africa, Australia and possibly South America. The name comes from Greek πρότερο- ("first") ...

s lacked these features and probably had a more sprawling posture.

Classification

Erythrosuchids were formerly classified as thecodonts of the suborder

Proterosuchia Proterosuchia is one of the suborders of the paraphyletic group Thecodontia; containing the most primitive and ancestral forms. These were primitive, vaguely crocodile-like, archosauriforms that mostly lived during the Early Triassic epoch. The ...

. This classification is no longer used by

paleontologist 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 ...

s, who now employ a

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

approach. In this, erythrosuchids constitute an

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 Gauthi ...

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

that is an outgroup to the Archosauria proper. The presence of certain archosaurian

features Feature may refer to: Computing * Feature (CAD), could be a hole, pocket, or notch * Feature (computer vision), could be an edge, corner or blob * Feature (software design) is an intentional distinguishing characteristic of a software item ...

, such as the triradiate pelvic girdle, the

, and the third

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the med ...

longer than the fourth, indicate that erythrosuchids are closer to the true archosaurs than the

Proterosuchidae Proterosuchidae is an early family of basal archosauriforms whose fossils are known from the Latest Permian and the Early Triassic of Europe, Asia, Africa, Australia and possibly South America. The name comes from Greek πρότερο- ("first" ...

, which lack these features. Thus the Erythrosuchidae occupy a transitional evolutionary position between the most primitive archisauriformes and more advanced Triassic archosaurs.

Genera

Phylogeny

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 d ...

from Parrish (1992): Below is a cladogram from Ezcurra (2016) that reexamined all historical members of the "Proterosuchia" (a

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

historical group including

s and

erythrosuchid 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 b ...

s). The placement of fragmentary taxa that had to be removed to increase tree resolution is indicated by dashed lines (in the most derived position that they can be confidently assigned to). Taxa that are ''

nomina dubia In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'' are indicated by the note "dubium". Bold terminal taxa are collapsed. Ezcurra (2016) recovered a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

Erythrosuchidae, although the relationship of the Long Reef form (SAM P41754) and '' Uralosaurus'' remain unknown within the family.

Paleobiology

The large contemporary

kannemeyeriid ''Kannemeyeria'' is a genus of dicynodont that lived during the Anisian age of Middle Triassic period in what is now Africa and South America. The generic name is given in honor of Dr. Daniel Rossouw Kannemeyer, the South African fossil collect ...

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typicall ...

s doubtless constituted much of erythrosuchids' prey. However, the first erythrosuchids appear in the fossil record slightly earlier than the kannemeyeriids, so it must be assumed that they fed on other animals as well.

References

Sources

* Benton, M. J. (2000), ''Vertebrate Paleontology'', 2nd Ed. Blackwell Science Ltd (2004) 3rd edition * Carroll, R. L. (1988), ''Vertebrate Paleontology and Evolution'', WH Freeman & Co.

External links

Erythrosuchidae

– list of species (Mikko's Phylogeny Archive) {{Taxonbar, from=Q133077 Erythrosuchids Prehistoric reptile families Olenekian first appearances Middle Triassic extinctions Taxa named by D. M. S. Watson