New species of Triassic-​era crocodile-​like reptile unearthed in Brazil

Aurantiacus Stenoscelida Mauricio S. Garcia created the skeleton; Matheus Fernandes rebuilt it.

Researchers from the Federal University of Santa Maria, in collaboration with a colleague from the Federal University of Juiz de Fora, have identified a new species of Triassic-era reptile discovered recently at a dig site in Brazil.

Rodrigo Temp Müller, Mauricio Silva Garcia, and André de Oliveira Fonseca describe the fossil they discovered and where the new species fits in the historical record in their paper published in the Journal of Systematic Palaeontology.

Paleontologists have been working at the Rio Grande do Sul dig site in Brazil for some time, and have discovered a large number of dinosaur bones. However, few reptile remains have been discovered during that time period.

As a result, the researchers were taken aback when they discovered a complete leg fossil from an unknown ancient reptile, as well as configurations of the foot that was once attached to it. The researchers knew the fossils were old because the rock around them was dated to 230 million years ago, when dinosaurs roamed the earth.

The fossil was later identified as belonging to an ancient class of reptiles known as proterochampsids, which had previously only been discovered in Argentina and Brazil. Prior research has revealed that, despite sharing physical characteristics with modern crocodiles and alligators, there is no strong degree of kinship.

The researchers also discovered that the fossil represented a previously unknown species, which allowed them to name it. Tenoscelida aurantiacus was chosen as a nod to the slenderness of the leg and the orange color of the rocky bed where it was discovered.

The researchers estimated the creature would have been 1.40 meters long and walked on all fours based on the size of the fossil. They also suspect that the reptile was a meat eater, based on similar species at the time. They believe its shape suited it to live near the water, similar to that of modern alligators.

The fossil Stenoscelida aurantiacus. Photographer: Rodrigo Temp Müller

The researchers point out that the fossil was in excellent condition, allowing them to identify leg structures that were similar to many of those seen in dinosaurs. They point out that the muscle fixation points indicate the creature was very strong.

More details: Rodrigo Temp Müller et al. Journal of Systematic Palaeontology, A new proterochampsid (Archosauriformes: Proterochampsia) from the Late Triassic of southern Brazil and the emergence of archosaurian hind limb traits (2022). DOI: 10.1080/14772019.2022.2128913


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