Jurassic park Clue to Pterosaur found in fossil of flightless ‘rabbit reptile’

Pterosaurs, the flying reptiles that lived alongside the dinosaurs, are an evolutionary mystery. They appear in the fossil record fully formed, some with 33-foot wingspans, and there is very little evidence of the ancestors that came before them. A new fossil, described Wednesday in the journal Nature, provides an elusive glimpse of a group of reptiles most closely related to pterosaurs.

“For the first time, we are looking into the face of a pterosaur precursor, and this animal is so bizarre,” said Rodrigo Temp Muller, a paleontologist at the Federal University of Santa Maria in Brazil and an author of the study. Dr. Muller found the fossil in 2022 while doing fieldwork in Rio Grande do Sul, Brazil’s southernmost state. He spotted a piece of thighbone in the rust-red earth, and “it was clear that it was a special fossil,” he said. The bone belonged to a lagerpetid, a group of animals whose name means “rabbit reptile.” Lagerpetids were once considered early relatives of dinosaurs, but a study published in 2020 provided evidence that they were actually more closely related to pterosaurs.

Lagerpetid fossils are in short supply, especially the bones from the animals’ heads and hands. Dr. Muller found, in addition to the thighbone, extensive remains, including the tip of a curved beak and a nearly complete lower arm, ending in curved claws shaped like scimitar blades.

Dr. Muller said that he and his fellow paleontologists had “no idea” what lagerpetids really looked like until they found this new specimen, and that their sharp beaks and claws struck him as “very strange.”

Dr. Muller and his colleagues named the creature Venetoraptor gassenae, which nods to its place of discovery near Vale Vêneto, its raptor-like features and Valserina Maria Bulegon Gassen, who helped found the Federal University of Santa Maria’s paleontology center

In life, 230 million years ago, Venetoraptor gassenae was about three feet long, including its tail, and weighed between nine and 18 pounds. Like many other early reptiles, its skin was most likely covered in feather-like filaments. Its hooked beak, Dr. Muller said, is “mysterious.” Similar structures in modern birds have various purposes, including tearing into flesh, attracting mates or eating fruit. Unlike its pterosaur relatives, Venetoraptor would not have been able to fly. However, Dr. Muller hypothesizes that Venetoraptor’s large hands and curved claws could have helped it to climb trees, a behavior that may have eventually led to jumping between branches, gliding and, eventually, true flight.

Analysing Venetoraptor’s skeletal traits and comparing them with its fellow Triassic reptiles revealed that the precursors of dinosaurs and pterosaurs were more diverse than previously thought. Dr. Muller said that the study challenges the belief that “earlier forms were simpler and fated to extinction to give space to the more evolved dinosaurs and pterosaurs.”

Emma Dunne, a paleontologist at the Friedrich Alexander University Erlangen-Nuremberg in Germany who was not involved with the study, said that when teaching, she often uses pterosaurs as an example of a fossil whose origins are murky. As such, she said, this discovery helps illuminate the pterosaur family tree.