Erythrosuchidae (meaning "red crocodiles" in

Greek Greek may refer to: 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 of all kno ...

) are a family of large basal

archosauriform Archosauriformes (Greek for 'ruling lizards', and Latin for 'form') is a clade of diapsid reptiles encompassing archosaurs and some of their close relatives. It was defined by Jacques Gauthier (1994) as the clade stemming from the last common anc ...

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

s that lived from the later Early

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

(

Olenekian In the geologic timescale, the Olenekian is an age (geology), age in the Early Triassic epoch (geology), epoch; in chronostratigraphy, it is a stage (stratigraphy), stage in the Lower Triassic series (stratigraphy), series. It spans the time betw ...

) to the early Middle Triassic (

Anisian In the geologic timescale, the Anisian is the lower stage (stratigraphy), stage or earliest geologic age, age of the Middle Triassic series (stratigraphy), series or geologic epoch, epoch and lasted from million years ago until million years ag ...

Naming

The family Erythrosuchidae was named by David Meredith Seares Watson 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 or superpredator, 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 hig ...

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 under ...

of the

Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe Khoemana (also known as !Orakobab or Korana) word is a semidesert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its extent is ...

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

Early Early may refer to: Places in the United States * Early, Iowa, a city * Early, Texas, a city * Early Branch, a stream in Missouri * Early County, Georgia * Fort Early, Georgia, an early 19th century fort Music * Early B, stage name of Jamaican d ...

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epoch (geology), epochs of the Triassic period (geology), period or the middle of three series (stratigraphy), series in which the Triassic system (stratigraphy), system is di ...

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

archosaur Archosauria () or archosaurs () is a clade of diapsid sauropsid tetrapods, with birds and crocodilians being the only extant taxon, extant representatives. Although broadly classified as reptiles, which traditionally exclude birds, the cladistics ...

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 sep ...

, which are found in other early archosauriformes, such as '' Doswellia'' 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 individual shops are all owned by individual franchisees. The chain has three ...

(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 mammals h ...

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

maxilla In vertebrates, the maxilla (: maxillae ) 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 two maxil ...

, 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 (; : is ...

. Although it is small, the

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

, 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 proterosuchids 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. Th ...

. This classification is no longer used by

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

s, who now employ a

cladistic Cladistics ( ; from Ancient Greek 'branch') 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 ...

approach. In this, erythrosuchids constitute an

Archosauriformes Archosauriformes (Ancient Greek, Greek for 'ruling lizards', and Latin for 'form') is a clade of diapsid reptiles encompassing Archosaur, archosaurs and some of their close relatives. It was defined by Jacques Gauthier (1994) as the clade stemmin ...

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

that is an

outgroup Outgroup may refer to: * Outgroup (cladistics), an evolutionary-history concept * Outgroup (sociology) In social psychology and sociology, an in-group is a social group to which a person psychologically identifies as being a member. By cont ...

to the Archosauria proper. The presence of certain archosaurian

features Feature may refer to: Computing * Feature recognition, could be a hole, pocket, or notch * Feature (computer vision), could be an edge, corner or blob * Feature (machine learning), in statistics: individual measurable properties of the phenome ...

, such as the triradiate pelvic girdle, the

, and the third

metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

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 Late Permian and the Early Triassic. The highest diversity of genera is known from European Russia, but fossils are also known from South Africa, India ...

, which lack these features. Thus the Erythrosuchidae occupy a transitional evolutionary position between the most primitive archisauriformes and more advanced Triassic archosaurs. The family was defined by Martin Ezcurra and colleagues in 2010 during the description of '' Koilamasuchus'' as "all taxa more closely related to ''

Erythrosuchus africanus ''Erythrosuchus'' (from , 'red' and , 'crocodile') is an extinct genus of archosauriform reptiles from the early Triassic of South Africa. Remains have been found from the Cynognathus Assemblage Zone of the Beaufort Group in the Karoo of South ...

'' than to '' Proterosuchus fergusi'' or ''Passer domesticus'' (the

house sparrow The house sparrow (''Passer domesticus'') is a bird of the Old World sparrow, sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pa ...

Genera

Phylogeny

Cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

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 that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

historical group including proterosuchids and erythrosuchids). 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 ...

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

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

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

Paleobiology

The large contemporary kannemeyeriid

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, t ...

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 Prehistoric reptile families Olenekian first appearances Middle Triassic extinctions Taxa named by D. M. S. Watson