''Buriolestes'' is a genus of early

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 lon ...

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

s from the

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

Santa Maria Formation The Santa Maria Formation is a sedimentary 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 early dinosaurs and other ...

of the

Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande d ...

in southern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. It contains a single species, ''B. schultzi'', named in 2016. The type specimen was found alongside a specimen of the

lagerpetid Lagerpetidae (; originally Lagerpetonidae) is a family of basal avemetatarsalians. Though traditionally considered the earliest-diverging dinosauromorphs (reptiles closer to dinosaurs than to pterosaurs), fossils described in 2020 suggest that ...

dinosauromorph '' Ixalerpeton''.

Discovery and naming

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

specimen, ULBRA-PVT280, was discovered in 2009 in the Buriol ravine in São João do Polêsine,

. These rocks are part of the

, which dates to the

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 m ...

epoch. The specimen consists of a single skeleton preserving parts of the skull, vertebrae, left forelimb, and left hindlimb. Another set of smaller bones is also present, which may belong to a juvenile or a different taxon altogether. Two individuals of '' Ixalerpeton'' were also preserved close by. Additional remains were discovered in 2015 and published in 2018. These include a mostly complete skeleton, CAPPA/UFSM 0035, which preserves a complete skull and most bones apart from tail vertebrae. Additional dinosaur bones from the Buriol locality may also belong to ''Buriolestes'', but their assignment is uncertain. They include a femur (ULBRA-PVT289), a portion of an individual's hip and hindlimbs (ULBRA-PVT056), and a lone axis vertebra (CAPPA/UFSM 0179). These new finds have made ''Buriolestes'' among the most complete Triassic dinosaurs known, comparable to ''

Eoraptor ''Eoraptor'' () is a genus of small, lightly built, basal sauropodomorph. One of the earliest-known dinosaurs, it lived approximately 231 to 228 million years ago, during the Late Triassic in Western Gondwana, in the region that is now northw ...

'', ''

Herrerasaurus ''Herrerasaurus'' is a genus of saurischian dinosaur from the Late Triassic period. This genus was one of the earliest dinosaurs from the fossil record. Its name means "Herrera's lizard", after the rancher who discovered the first specimen i ...

'', and ''

Coelophysis ''Coelophysis'' ( traditionally; or , as heard more commonly in recent decades) is an extinct genus of coelophysid theropod dinosaur that lived approximately 228 to 201.3 million years ago during the latter part of the Triassic Period fro ...

''. In 2016, the holotype specimen was described and given the generic name ''Buriolestes,'' after the Buriol family; the suffix ''-lestes'' is Greek for "robber." The specific name honors palaeontologist Cezar Schultz. The well-preserved additional specimens were described in 2018, with the braincase of CAPPA/UFSM 0035 being described in more detail in 2020.

Description

Although ''Buriolestes'' superficially resembles predatory

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

dinosaurs, with jaws lined by finely serrated and slightly curved teeth well-adapted to a carnivorous diet, it is in fact an early member of the otherwise-herbivorous

Sauropodomorpha 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 lon ...

, the group that gave rise to the giant

sauropods Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

. Characteristically sauropodomorph traits seen in ''Buriolestes'' include a downturned jaw tip and a long deltopectoral crest on the

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a r ...

. However, ''Buriolestes'' also lacks a small head and enlarged nostrils, which are typical among sauropodomorphs, and the medial condyle on the end of its tibia projects backwards, a distinctive feature (

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to ...

) unique to this animal. In ''Buriolestes'', the shaft of the pubis is straight, in contrast to later sauropodomorphs, where it has been modified into an expanded "apron," theropods, where it forms a "boot," and all

ornithischia Ornithischia () is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek ...

ns, where it is reversed and is parallel to the

ischium The ischium () form ...

. Additional traits differentiate ''Buriolestes'' from both later and contemporary sauropodomorphs: the front expansion ( preacetabular ala) of the ilium is relatively tall, the outer edges of the pubis are bevelled, the

trochanter A trochanter is a tubercle of the femur near its joint with the hip bone. In humans and most mammals, the trochanters serve as important muscle attachment sites. Humans are known to have three trochanters, though the anatomic "normal" includes ...

of the femur forms a shelf, and the

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 me ...

of the fifth digit on the foot is relatively long.

Classification

A phylogenetic analysis conducted in 2016 affirmed the

affinities of ''Buriolestes''. Part of the phylogenetic tree from the study is shown below. Five variants of phylogenetic analyses published earlier were used along with the description of the new specimens in 2018. One of these analyses, based on Langer ''et al.'' (2017) placed ''Buriolestes'' in a clade of early sauropodomorphs, alongside ''Eoraptor'', '' Panphagia'', '' Pampadromaeus'', and ''

Saturnalia Saturnalia is an ancient Roman festival and holiday in honour of the god Saturn, held on 17 December of the Julian calendar and later expanded with festivities through to 23 December. The holiday was celebrated with a sacrifice at the Temple ...

''. Another analysis, which used the dataset of ''Buriolestes''' original description with the added parameter of

implied weighting Implied weighting describes a group of methods used in phylogenetic analysis to assign the greatest importance to characters that are most likely to be homologous. These are a posteriori methods, which include also dynamic weighting, as opposed t ...

, placed it as the sister taxon to ''Eoraptor'', with the ''Buriolestes''+''Eoraptor'' clade sister to a clade connecting ''Panphagia'' and ''Pampadromaeus''. The other three analyses, which also corresponded to the original description's dataset, agreed with that study's placement of ''Buriolestes'' as the single most basal sauropodomorph.

Paleoecology

The shape of the teeth of ''Buriolestes'' suggest that it was a carnivore which fed on small vertebrates and invertebrates, which provides evidence that

sauropodomorphs 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 lon ...

- and likely all

saurischia Saurischia ( , meaning "reptile-hipped" from the Greek ' () meaning 'lizard' and ' () meaning 'hip joint') is one of the two basic divisions of dinosaurs (the other being Ornithischia), classified by their hip structure. Saurischia and Ornithis ...

ns and

s as a whole - were ancestrally carnivorous, and that sauropodomorphs,

ns, and various groups of

s independently became herbivorous. The co-occurrence of ''Buriolestes'' and '' Ixalerpeton'' parallels the simultaneous presence of dinosaurs and non-dinosaur

dinosauromorphs Dinosauromorpha is a clade of avemetatarsalian archosaurs (reptiles 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 lage ...

at other sites (such as the

Ischigualasto Ischigualasto Provincial Park ( es, Parque Provincial Ischigualasto), also called ''Valle de la Luna'' ("Valley of the Moon" or "Moon Valley"), due to its moon like appearance, is a provincial protected area in the north-east of San Juan Provin ...

and Chinle Formations), suggesting that, after their initial

evolutionary radiation An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. Radiations may affect one clade or many, and be rapid ...

, dinosaurs did not rapidly replace their dinosauromorph precursors.

References

{{Portal bar, Brazil, Dinosaurs, Paleontology Sauropodomorphs Carnian genera Late Triassic dinosaurs of South America Triassic Brazil Fossils of Brazil Santa Maria Formation Fossil taxa described in 2016 Taxa named by Alexander Kellner

Discovery and naming

Description

Classification

Paleoecology

See also

References