Brazilian researchers may have elucidated a strange case of identity switching that dates back to 225 million years ago, at the beginning of the Age of Dinosaurs. According to scientists, fossils from Rio Grande do Sul originally classified as one of the oldest flying reptiles in the world actually correspond to land animals — and two different species.
“It’s a good example of how science works — the conclusions of any study are provisional and can be revised”, says paleontologist Marina Bento Soares, from the National Museum at UFRJ (Federal University of Rio de Janeiro).
She signs off on both the new fossil research and the original 2010 work in which the animal known as Faxinalipterus minimus was presented to the scientific community. The suffix “pterus” of the official name comes from the Greek term for “wing” and indicated that the species would be a pterosaur, or winged reptile.
The name is still valid, but the most accurate analysis of the fossilized bones, which has just appeared in the scientific journal PeerJ, indicates that the remains previously attributed to the pterosaur include yet another species, which paleontologists have named Maehary Bonapartei. Neither animal would have been able to fly across the skies of the Triassic period, when they lived, but both would be part of the broader lineage of reptiles from which the pterosaur branch sprang.
Alongside Soares, Alexander Kellner, current director of the National Museum, and Rodrigo Temp Müller, from the Federal University of Santa Maria, as well as researchers from other institutions in Brazil and abroad, also participate in the study.
The fossils originally described as the pterosaur F. minimus were found in rocks in the municipality of Faxinal do Soturno (RS) that proved to be one of the richest deposits documenting the beginning of the Age of Dinosaurs. At the time, gaucho paleontologists were collaborating with renowned Argentine researcher José Fernando Bonaparte, who died in 2020.
It turns out, however, that the bones attributed to the animal were found on two different occasions. First came the postcranial (ie from the neck down of the animal) fossils, such as limb fragments, and then a piece of the left jaw.
“The maxilla had a very striking feature: the teeth were widely spaced, thin and pointed. And this was a very striking feature of Triassic pterosaurs, like some species from the Alps, Italy and Austria”, says Soares, who At the time, he was working at the Federal University of Rio Grande do Sul.
This led the Argentine Bonaparte, who was captaining the work at the time, to hit the hammer and classify the animal as a winged reptile.
There was one flea left behind the ear, though—the fact that you couldn’t be sure that the jaw and the other bones actually belonged to the same animal. Furthermore, already in 2010, after the original publication of the description of the faxinalipterusAlexander Kellner, one of the world’s leading experts on pterosaurs, analyzed the findings and was not convinced that the fossils actually corresponded to a winged reptile.
The fossils were on loan to the National Museum for Kellner and other collaborators to re-examine, and were at the institution when the great fire of September 2018 destroyed much of its collection. “Part of the material faxinalipterus survived the fire, but the current state of conservation unfortunately doesn’t even compare to what it was before”, laments the paleontologist.
Much of the reanalysis, however, was already done. It was then that the researchers learned that other fossils had been found in the same rocks in Rio Grande do Sul, with characteristics very similar to those of the 2010 jaw. And data obtained from CT scans had shown that the “separate” teeth, supposedly “of a pterosaur” , were just an illusion: in fact, the maxilla had several alveoli (the spaces of tooth insertion) that had lost their teeth during the animal’s decomposition and fossilization process.
These data, added to a new analysis of the postcranial elements, led to the dismemberment of the fossils into two different species: on the one hand, the Maehary Bonaparteirepresented mainly by the maxilla and other pieces of the skull, and on the other the faxinalipterus, corresponding to the bones of the limbs. Comparisons of the anatomy of these bones with that of other reptiles of the period indicate that both animals would be cousins ​​of pterosaurs, but without any adaptations associated with flight, or even the ability to glide.
The kinship, however, is close enough to motivate Kellner to continue the search for the first winged reptiles or their direct ancestors in the same region. The task is complicated, as the fossil record has not yet revealed the details of this evolutionary transition between the earth and the air.
“I wrote in one of my books that one of my dreams is to find a reptile that is dying to turn into a pterosaur,” he jokes. “The rocks of Rio Grande do Sul are an excellent place for that.”
In fact, the site is also important for documenting the early diversification of a number of other related groups of reptiles, such as the dinosaurs themselves.
