''Erythrovenator'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of basal

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

of Rio Grande so Sul,

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. The genus contains a single species, ''Erythrovenator jacuiensis''.

Discovery

The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

and only known specimen of ''Erythrovenator'', CAPPA/UFSM 0157, is an isolated

proximal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

portion of the left

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

. This fossil was found in red

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

of the Niemeyer Site, near Agudo in Rio Grande Sul. The site is tentatively considered to be early

Norian The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...

(or possible late

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

) in age and belongs the Candelária Sequence of the

Santa Maria Supersequence The Santa Maria Formation is a sedimentary geological formation, rock formation found in Rio Grande do Sul, Brazil. It is primarily Carnian in age (Late Triassic), and is notable for its fossils of cynodonts, "rauisuchian" pseudosuchians, and ear ...

. No other

dinosauromorphs Dinosauromorpha is a clade of avemetatarsalians (archosaurs closer to birds than to crocodilians) that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lagerpetids, ...

are known from this site, which is dominated by the

traversodontid Traversodontidae is an extinct family of herbivorous cynodonts. Traversodonts were primarily Gondwanan, with many species known from Africa and South America. Recently, traversodonts have also been found from Europe and North America. Traversodon ...

cynodont Cynodontia () is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 Megaannum, mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extin ...

Siriusgnathus ''Siriusgnathus'' is a traversodontid cynodont from the Carnian channel sandstones and mudstones of the Candelária Formation, belonging to the Santa Maria Supersequence of the Paraná Basin in southeastern Brazil.

''. The site probably corresponds to the ''Riograndia'' Assemblage Zone based on the presence of ''Siriusgnathus''. The generic name, ''Erythrovenator'', is derived from the Greek word ερυθρός (''erythrós''), meaning "red" (in reference to the color of the holotype), and the Latin word vēnātor, meaning "hunter." The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, ''jacuiensis'', references a nearby river, the

Jacuí River The Jacuí River () is a river in Rio Grande do Sul state of southern Brazil. The Jacuí empties into the Guaíba River, an estuarine arm of the Lagoa dos Patos, a large coastal lagoon connected to the Atlantic Ocean. Sources The Jacuí River, k ...

Description

Although only partially preserved, the femur has an estimated total length of about 190 millimeters (7.5 inches). The femoral head has a strongly concave lower edge, a rounded inner edge, and a distinct anterolateral tuber, all characteristics of dinosaur femora. It also had small anteromedial and posteromedial tubers, with the former structure quite different from the folded anteromedial tuber of other theropods. The rear surface of the femoral head has a thin vertical ridge in its

medial Medial may refer to: Mathematics * Medial magma, a mathematical identity in algebra Geometry * Medial axis, in geometry the set of all points having more than one closest point on an object's boundary * Medial graph, another graph that repr ...

portion and a raised scar in its lateral portion, similar to ''

Buriolestes ''Buriolestes'' is a genus of early sauropodomorph dinosaurs from the Late Triassic Santa Maria Formation of the Paraná Basin in southern Brazil. It contains a single species, ''B. schultzi'', named in 2016. The type specimen was found alongsid ...

''. There is no evidence for a dorsolateral trochanter, unlike all other known Triassic dinosaurs. On the other hand, the anterior trochanter is a prominent pyramidal structure offset from the shaft by a cleft. This is most similar to

neotheropods Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodomor ...

among early dinosaurs, and is also observed in some

silesaurids Silesauridae is an extinct family of Triassic dinosauriforms. It is most commonly considered to be a clade of non-dinosaur dinosauriforms, and the sister group of dinosaurs. Some studies have instead suggested that most or all silesaurids compr ...

. Although there is no distinct trochanteric shelf, the anterior trochanter does have a plate-like medial extension.

Classification

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

placed ''Erythrovenator'' as the most basal theropod, supported by the structure of the anterior trochanter. This would make it one of the oldest verifiable theropods known and one of the few known from the Triassic of Brazil. Other potentially older theropods include ''

Eodromaeus ''Eodromaeus'' (meaning "dawn runner") is an extinct genus of probable basal (phylogenetics), basal theropod dinosaurs from the Late Triassic of Argentina. Like many other of the earliest-known dinosaurs, it hails from the Carnian-age (~230 Ma) I ...

'' (from

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

), potentially ''

Nhandumirim ''Nhandumirim'' (meaning "small Rhea (bird), rhea" in the Tupi language) is a genus of basal Sauropodomorpha, sauropodomorph dinosaur from the Carnian age of Late Triassic Brazil. It is currently considered a Saturnaliidae, saturnaliid sauropodom ...

'' (also from Brazil), and herrerasaurids, but these taxa are not universally considered theropods. ''Nhandumirim'' is now considered to be a basal

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lo ...

. ''

Lepidus Marcus Aemilius Lepidus (; 89 BC – late 13 or early 12 BC) was a Roman general and statesman who formed the Second Triumvirate alongside Octavian and Mark Antony during the final years of the Roman Republic. Lepidus had previously been ...

'' and ''

Camposaurus ''Camposaurus'' ( ) is a coelophysid dinosaur genus from the Norian stage of the Late Triassic period of North America. The pertinent fossil remains date back to the early to middle Norian stage, and is widely regarded as the oldest known neothe ...

,'' a pair of coelophysids from the

United States of America The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguo ...

, are the only other agreed-upon theropods which may have a similar age to ''Erythrovenator''.

References

{{Taxonbar, from=Q102381502 Theropoda Dinosaur genera Carnian dinosaurs Norian dinosaurs Santa Maria Formation Dinosaurs of Brazil Fossil taxa described in 2021 Taxa named by Rodrigo T. Müller