Buriolestes

Lore & Background

The holotype specimen, ULBRA-PVT280, was discovered in 2009 in the Buriol ravine in São João do Polêsine, Brazil, in rocks of the Santa Maria Formation dating to the Carnian epoch. It consists of a single skeleton preserving parts of the skull, vertebrae, left forelimb, and left hindlimb. Another set of smaller bones may belong to a juvenile or a different taxon. A single individual of the lagerpetid pterosauromorph Ixalerpeton was also preserved close by. Additional remains discovered in 2015 and published in 2018 include a mostly complete skeleton, CAPPA/UFSM 0035, preserving a complete skull and most bones apart from tail vertebrae. Other dinosaur bones from the Buriol locality may also belong to Buriolestes, but their assignment is uncertain.

Reader's Guide

Buriolestes is significant because it provides key evidence that sauropodomorphs—and likely all saurischians and dinosaurs as a whole—were ancestrally carnivorous, and that herbivory evolved independently in different dinosaur groups. Its teeth, adapted for a carnivorous diet, contrast with the later herbivorous sauropodomorphs. A 2020 study of its endocranial anatomy indicated a brain morphology similar to crocodiles, with well-developed optic lobes suggesting sight-based predation and a comparatively underdeveloped olfactory bulb. The co-occurrence of Buriolestes and Ixalerpeton parallels the simultaneous presence of dinosaurs and non-dinosaur dinosauromorphs at other sites, suggesting that after their initial evolutionary radiation, dinosaurs did not rapidly replace their dinosauromorph precursors. A 2022 micro-computed tomography scan showed that Buriolestes lacked an invasive air sac system, indicating that pneumatisation in archosaur groups evolved independently at least three times.

Did You Know?

• Buriolestes was named after the Buriol family, with the suffix -lestes meaning 'robber' in Greek.
• The type specimen was found alongside a specimen of the lagerpetid pterosauromorph Ixalerpeton.
• Skeletally mature specimens exhibit size disparity, with one robust individual weighing over 15.4 kg and others between 6.4–7.2 kg.
• A 2020 study found that Buriolestes had a higher encephalisation quotient than sauropods such as Diplodocus, Nigersaurus, and Brachiosaurus.

The Buriol Discovery and a Growing Record

In 2009, a single skeleton was unearthed in the Buriol ravine at São João do Polêsine, southern Brazil, within the Carnian-age Santa Maria Formation. The holotype, catalogued as ULBRA-PVT280, preserved fragments of the skull, a series of vertebrae, and the complete left forelimb and hindlimb. Tucked among the bones were smaller elements that might belong to a juvenile or an entirely different animal, and just nearby lay two individuals of the pterosauromorph Ixalerpeton. The specimen was formally described in 2016 and named Buriolestes schultzi, a generic name honouring the Buriol family with the Greek suffix meaning "robber," while the specific epithet pays tribute to palaeontologist Cezar Schultz. The story did not end there. In 2015, a far more complete skeleton—CAPPA/UFSM 0035—was recovered, preserving a full skull and nearly every bone except the tail vertebrae. Its braincase received a dedicated anatomical treatment in 2020. A handful of additional elements, including a femur, a partial hip and hindlimb, and a single axis vertebra, may also belong to the genus, though their assignment remains uncertain. Together, these finds place Buriolestes among the most thoroughly documented Triassic dinosaurs, rivaling the completeness of Eoraptor, Herrerasaurus, and Coelophysis.

A Meat-Eater in the Sauropod Line

At first glance, Buriolestes looks like a small predatory theropod. Its jaws carry finely serrated, gently curved teeth clearly built for slicing flesh, and the animal likely hunted small vertebrates and soft-bodied invertebrates. Yet it sits firmly within Sauropodomorpha, the lineage that would eventually produce the colossal, plant-eating sauropods. This paradox is resolved by a mosaic of anatomy. Buriolestes shows hallmark sauropodomorph features such as a downturned jaw tip and an elongated deltopectoral crest on the humerus, yet it lacks the tiny skull and enlarged nostrils that characterise later members of the group. Its tibia bears a backwards-projecting medial condyle, a trait unique to this genus. The pubis shaft runs straight, unlike the expanded "apron" of later sauropodomorphs, the "boot" shape of theropods, or the reversed orientation seen in ornithischians. Other distinguishing details include a tall preacetabular ala on the ilium, bevelled pubis margins, a shelf-like femoral trochanter, and a relatively long fifth metatarsal. Skeletally mature individuals show notable size variation: a robust specimen from the Piche site exceeds 15.4 kilograms, while others range between 6.4 and 7.2 kilograms.

Mind, Senses, and the Absence of Air Sacs

A 2020 endocranial study led by Rodrigo T. Müller revealed that Buriolestes possessed a brain architecture closely resembling that of modern crocodiles. The optic lobes were well developed, pointing to a predator that relied heavily on vision, while the olfactory bulb was comparatively modest. Remarkably, the overall brain volume yielded a higher encephalisation quotient than that of giant sauropods such as Diplodocus, Nigersaurus, and Brachiosaurus. The flocculus, a region associated with balance and coordination, was notably well developed and matched the condition seen in Saturnalia, leading the authors to propose it as the ancestral state for all sauropodomorphs. Two years later, Aureliano and colleagues used micro-computed tomography to scan the postcranial skeletons of Buriolestes alongside other early saurischians, including Gnathovorax and Pampadromaeus. The scans showed no evidence of an invasive air-sac system and no pneumatization of the bones. This finding carries a major implication: the hollow, air-filled bones seen in pterosaurs, theropods, and sauropodomorphs are not inherited from a common ancestor but evolved independently at least three separate times across the archosaur tree.

Where Buriolestes Sits on the Tree of Life

The 2016 description confirmed Buriolestes as a sauropodomorph, but its exact position within that group has remained debated. Five phylogenetic analyses published in 2018 produced slightly different placements. One, drawing on the Langer et al. 2017 framework, nested Buriolestes within a broader clade that also included Eoraptor, Panphagia, Pampadromaeus, and Saturnalia. A second analysis, applying implied weighting to the original dataset, positioned Buriolestes as the direct sister taxon to Eoraptor, with that pair forming a clade sister to the Panphagia–Pampadromaeus grouping. The remaining three analyses, all using the original description's character matrix, recovered Buriolestes as the single most basal sauropodomorph. Beyond its taxonomic position, Buriolestes carries a profound evolutionary message. Its carnivorous dentition provides strong evidence that sauropodomorphs—and by extension all saurischians and dinosaurs—were ancestrally meat-eating, with herbivory evolving independently in sauropodomorphs, ornithischians, and several theropod lineages. Its co-occurrence with the non-dinosaur Ixalerpeton mirrors patterns at Ischigualasto and Chinle, suggesting that dinosaurs did not swiftly displace their dinosauromorph relatives after their initial radiation.

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