Buriolestes

Chapter • Meet the dinosaur

Overview

Buriolestes schultzi was a small, lightly built dinosaur barely two metres long from snout to tail tip, probably weighing around ten kilograms. It stood on two long, slender hind limbs, while the arms were much shorter and ended in grasping hands with curved claws. The skull was low and narrow with large eye sockets, and the jaws carried recurved, serrated teeth of exactly the kind seen in predatory dinosaurs. The neck was short compared with its later relatives, and the long tail acted as a counterweight during running. No feathers or filament-like body covering are known from Buriolestes or its closest relatives, so it is normally reconstructed with scaly or leathery skin. The surprise lies in where Buriolestes sits on the family tree. It belongs to Sauropodomorpha, the same lineage that later produced giants such as Brachiosaurus and Argentinosaurus. Yet Buriolestes was no plant-eater. Its teeth, jaws and lightweight skeleton show that it hunted small prey: insects, small reptiles and other little vertebrates sharing the same landscape. The discovery therefore became key evidence that the ancestors of the sauropods started out as fast-moving predators and only later shifted to a plant diet. A nearly complete braincase endocast published in 2018 showed that the brain weighed only about one and a half grams, but was organised much like that of small predatory theropods, with well-developed visual centres and a large flocculus, the part of the cerebellum that stabilises gaze during rapid head and body movements. That points to an active hunting lifestyle with sharp vision and good balance. In later, herbivorous sauropodomorphs the flocculus shrank as the animals grew heavier and slower. Buriolestes was described in 2016 by Sérgio Furtado Cabreira and colleagues, based on material from the Buriol ranch near São João do Polêsine in Rio Grande do Sul, southern Brazil. The genus name combines the landowners' surname with Greek lestes, "robber", and the species name honours the Brazilian palaeontologist Cesar Leandro Schultz. The same beds also yielded Ixalerpeton, a small lagerpetid — a dinosaur-like reptile that was not itself a dinosaur — showing that early dinosaurs lived alongside their close precursors. A second, far more complete skeleton described in 2018 made Buriolestes one of the best-known of all very early dinosaurs.

Chapter • Where it lived

Habitat

Buriolestes lived in the Late Triassic, during the Carnian stage about 233 million years ago. Every known fossil comes from the Santa Maria Formation of Rio Grande do Sul in southern Brazil, specifically the Buriol site near São João do Polêsine. At the time the region lay in the interior of the supercontinent Pangaea, a landscape of river valleys and broad floodplains with strongly seasonal wet and dry periods. Other reptile groups such as rhynchosaurs and cynodonts still dominated the fauna, while dinosaurs were small and comparatively rare members of the community.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy