Buriolestes

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Buriolestes
Temporal range: Late Triassic (Carnian)
~233  Ma
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Foto do bloco com o buriolestes Foto Flavio Lopes (Ufrgs).jpg
Block containing the holotype fossil
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Sauropodomorpha
Genus: Buriolestes
Cabreira et al. 2016
Species:
B. schultzi
Binomial name
Buriolestes schultzi
Cabreira et al. 2016

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 alongside a specimen of the lagerpetid dinosauromorph Ixalerpeton . [1]

Discovery and naming

The holotype specimen, ULBRA-PVT280, was discovered in 2009 in the Buriol ravine in São João do Polêsine, Brazil. [1] [2] These rocks are part of the Santa Maria Formation, which dates to the Carnian 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. [1]

Additional remains were discovered in 2015 and published in 2018. [2] [3] 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 , Herrerasaurus , and Coelophysis . [3]

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. [1] The well-preserved additional specimens were described in 2018, [3] with the braincase of CAPPA/UFSM 0035 being described in more detail in 2020. [2] [4]

Description

A size comparison between an average human male and a Buriolestes schultzi specimen Buriolestes schultzi size comparison.png
A size comparison between an average human male and a Buriolestes schultzi specimen
Skull diagram Buriolestes skull color coded.png
Skull diagram

Although Buriolestes superficially resembles predatory theropod dinosaurs, with jaws lined by finely serrated and slightly curved teeth well-adapted to a carnivorous diet, possibly preying on small vertebrates and soft invertebrates, it is in fact an early member of the otherwise-herbivorous Sauropodomorpha, the group that gave rise to the giant sauropods. [1] Characteristically sauropodomorph traits seen in Buriolestes include a downturned jaw tip and a long deltopectoral crest on the humerus. However, Buriolestes also lacks a small head and enlarged nostrils, [2] which are typical among sauropodomorphs, and the medial condyle on the end of its tibia projects backwards, a distinctive feature (autapomorphy) unique to this animal. [1]

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 ornithischians, where it is reversed and is parallel to the ischium. 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 of the femur forms a shelf, and the metatarsal of the fifth digit on the foot is relatively long. [1]

Skeletally mature specimens of Buriolestes exhibit intraspecific variation through size disparity, with one robust individual weighing over 15.4 kg (34 lb) and others weighing between 6.4–7.2 kg (14–16 lb). This robust specimen is collected from the Piche site, which makes it the first Buriolestes specimen outside the type locality. [5]

In 2022, Aureliano and colleagues performed a mirco-computed tomography scan on the postcranial skeletons of some of the earliest saurischian dinosaurs that lived during the late Carnian including Gnathovorax with sauropodomorphs Pampadromaeus and Buriolestes, which showed that the invasive air sac system was absent and that their bones were not pneumatised. These results indicate that pneumatisation in archosaur groups (pterosaurs, theropods and sauropodomorphs) are not homologous, but are traits that independently evolved at least 3 times. [6]

Classification

A close-up of the holotype's teeth Buriolestes teeth.jpg
A close-up of the holotype's teeth

A phylogenetic analysis conducted in 2016 affirmed the sauropodomorph affinities of Buriolestes. Part of the phylogenetic tree from the study is shown below. [1]

Dinosauria

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) [7] placed Buriolestes in a clade of early sauropodomorphs, alongside Eoraptor, Panphagia , Pampadromaeus , and Saturnalia . Another analysis, which used the dataset of Buriolestes' original description with the added parameter of implied weighting, 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. [3]

Paleoecology

Restoration of Buriolestes schultzi Buriolestes schultzi restoration.png
Restoration of Buriolestes schultzi

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 - and likely all saurischians and dinosaurs as a whole - were ancestrally carnivorous, and that sauropodomorphs, ornithischians, and various groups of theropods independently became herbivorous. [1]

The co-occurrence of Buriolestes and Ixalerpeton parallels the simultaneous presence of dinosaurs and non-dinosaur dinosauromorphs at other sites (such as the Ischigualasto [8] and Chinle [9] Formations), suggesting that, after their initial evolutionary radiation, dinosaurs did not rapidly replace their dinosauromorph precursors. [1]

See also

Related Research Articles

<i>Eoraptor</i> Extinct genus of dinosaurs

Eoraptor is a genus of small, lightly built, basal sauropodomorph dinosaur. One of the earliest-known dinosaurs and one of the earliest members of the sauropod family, it lived approximately 231 to 228 million years ago, during the Late Triassic in Western Gondwana, in the region that is now northwestern Argentina. The type and only species, Eoraptor lunensis, was first described in 1993, and is known from an almost complete and well-preserved skeleton and several fragmentary ones. Eoraptor had multiple tooth shapes, which suggests that it was omnivorous. Eoraptor was 1.5 feet (0.46 m) tall and 3 feet (0.91 m) long.

<span class="mw-page-title-main">Sauropodomorpha</span> Extinct clade of dinosaurs

Sauropodomorpha 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 long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The prosauropods, which preceded the sauropods, were smaller and were often able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the Late Triassic until their decline and extinction at the end of the Cretaceous.

<i>Staurikosaurus</i> Extinct genus of dinosaurs

Staurikosaurus is a genus of herrerasaurid dinosaur from the Late Triassic of Brazil, found in the Santa Maria Formation.

<i>Saturnalia tupiniquim</i> Extinct genus of dinosaurs

Saturnalia is an extinct genus of basal sauropodomorph dinosaur known from the Late Triassic Santa Maria Formation of Rio Grande do Sul, southern Brazil. It is one of the earliest known dinosaurs.

<span class="mw-page-title-main">Herrerasauridae</span> Extinct family of basal saurischian dinosaurs

Herrerasauridae is a family of carnivorous dinosaurs, possibly basal to either theropods or even all of saurischians, or even their own branching from Dracohors, separate from Dinosauria altogether. They are among the oldest known dinosaurs, first appearing in the fossil record around 233.23 million years ago, before becoming extinct by the end of the Carnian stage. Herrerasaurids were relatively small-sized dinosaurs, normally no more than 4 metres (13 ft) long, although the holotype specimen of "Frenguellisaurus ischigualastensis" is thought to have reached around 6 meters long. The best known representatives of this group are from South America, where they were first discovered in the 1930s in relation to Staurikosaurus and 1960s in relation to Herrerasaurus. A nearly complete skeleton of Herrerasaurus ischigualastensis was discovered in the Ischigualasto Formation in San Juan, Argentina, in 1988. Less complete possible herrerasaurids have been found in North America and Africa, and they may have inhabited other continents as well.

<i>Herrerasaurus</i> Extinct genus of dinosaurs

Herrerasaurus is likely 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 in 1958 in South America. All known fossils of this carnivore have been discovered in the Ischigualasto Formation of Carnian age in northwestern Argentina. The type species, Herrerasaurus ischigualastensis, was described by Osvaldo Reig in 1963 and is the only species assigned to the genus. Ischisaurus and Frenguellisaurus are synonyms.

<i>Guaibasaurus</i> Extinct genus of dinosaurs

Guaibasaurus is an extinct genus of basal saurischian dinosaur known from the Late Triassic Caturrita Formation of Rio Grande do Sul, southern Brazil. Most analyses recover it as a sauropodomorph, although there are some suggestions that it was a theropod instead. In 2016 Gregory S. Paul estimated it at 2 meters and 10 kg, whereas in 2020 Molina-Pérez and Larramendi listed it at 3 meters and 35 kg.

<i>Lewisuchus</i> Extinct genus of reptiles

Lewisuchus is a genus of archosaur that lived during the Late Triassic. As a silesaurid dinosauriform, it was a member of the group of reptiles most commonly considered to be the closest relatives of dinosaurs. Lewisuchus was about 1 metre (3.3 ft) long. Fossils have been found in the Chañares Formation of Argentina. It exhibited osteoderms along its back.

<span class="mw-page-title-main">Dinosauromorpha</span> Clade of reptiles

Dinosauromorpha is a clade of avemetatarsalians that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lagerpetids, with later formulations specifically excluding pterosaurs from the group. Birds are the only dinosauromorphs which survive to the present day.

<span class="mw-page-title-main">Santa Maria Formation</span> Geologic formation in Brazil

The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It is primarily Carnian in age, and is notable for its fossils of cynodonts, "rauisuchian" pseudosuchians, and early dinosaurs and other dinosauromorphs, including the herrerasaurid Staurikosaurus, the basal sauropodomorphs Buriolestes and Saturnalia, and the lagerpetid Ixalerpeton. The formation is named after the city of Santa Maria in the central region of Rio Grande do Sul, where outcrops were first studied.

<span class="mw-page-title-main">São João do Polêsine</span> Municipality in Rio Grande do Sul, Brazil

São João do Polêsine is a municipality in the state of Rio Grande do Sul, Brazil.

<i>Panphagia</i> Extinct genus of dinosaurs

Panphagia is a genus of sauropodomorph dinosaur described in 2009. It lived around 231 million years ago, during the Carnian age of the Late Triassic period in what is now northwestern Argentina. Fossils of the genus were found in the La Peña Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin. The name Panphagia comes from the Greek words pan, meaning "all", and phagein, meaning "to eat", in reference to its inferred omnivorous diet. Panphagia is one of the earliest known dinosaurs, and is an important find which may mark the transition of diet in early sauropodomorph dinosaurs.

<span class="mw-page-title-main">Saturnaliidae</span> Late Triassic dinosaur clade

Saturnaliidae is a family of basal sauropodomorph dinosaurs found in Brazil, Argentina and possibly Zimbabwe. It is not to be confused with Saturnalidae, a family of radiolarian protists.

<i>Eodromaeus</i> Extinct genus of dinosaurs

Eodromaeus is an extinct genus of probable basal theropod dinosaurs from the Late Triassic of Argentina. Like many other of the earliest-known dinosaurs, it hails from the Carnian-age Ischigualasto Formation, within the Ischigualasto-Villa Unión Basin of northwestern Argentina. Upon its discovery, it was argued to be one of the oldest true theropods, supplanting its contemporary Eoraptor, which was reinterpreted as a basal sauropodomorph.

Pampadromaeus is an extinct genus of basal sauropodomorph dinosaurs known from the Late Triassic (Carnian) Santa Maria Formation of the Paraná Basin in Rio Grande do Sul, southern Brazil.

Ixalerpeton is a genus of lagerpetid avemetatarsalian containing one species, I. polesinensis. It lived in the Late Triassic of Brazil alongside the sauropodomorph dinosaur Buriolestes.

<i>Macrocollum</i> Extinct genus of dinosaurs

Macrocollum is a genus of unaysaurid sauropodomorph dinosaur that lived during the Late Triassic period in what is now Brazil. It is one of the oldest dinosaurs known.

<i>Nhandumirim</i> Genus of reptiles (fossil)

Nhandumirim is a genus of basal sauropodomorph dinosaur from the Carnian age of Late Triassic Brazil. It is currently considered a saturnaliid sauropodomorph. The type and only species, Nhandumirim waldsangae, is known from a single immature specimen including vertebrae, a chevron, pelvic material, and a hindlimb found in the Santa Maria Formation in Rio Grande do Sul.

<i>Gnathovorax</i> Species of dinosaur

Gnathovorax is a genus of herrerasaurid saurischian dinosaur from the Santa Maria Formation in Rio Grande do Sul, Brazil. The type and only species is Gnathovorax cabreirai, described by Pacheco et al. in 2019.

Erythrovenator is a genus of basal theropod dinosaurs from the Late Triassic of Rio Grande so Sul, Brazil. The genus contains a single species, Erythrovenator jacuiensis.

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