A new Brazilian reptile 225 million years old

In a new study published in PeerJ — Reassessment of Faxinalipterus minimus, a purported Triassic pterosaur from southern Brazil has resulted in the description of a new taxon — researchers present maehary bonaparte a small reptile considered the most basal in the evolutionary line that gave rise to pterosaurs. The study also shows that Faxinalipterus minimus is not a winged reptile, contrary to what was previously assumed.

maehary bonaparte represents a small reptile considered the most basal of the evolutionary line that gave rise to pterosaurs. The study also shows that Faxinalipterus minimus is not a winged reptile, contrary to what was previously assumed.

Researchers from the National Museum/UFRJ, the Federal University of Santa Maria, the Catalan Institute of Paleontology, the Regional University of Cariri, the Federal University of Pampa, the Federal University of Rio Grande do Sul and COPPE/UFRJ presented an examination of a small reptile named Faxinalipterus minimus, from Triassic rocks (about 225 million years ago) in Rio Grande do Sul. Faxinalipterus was described over ten years ago (2010), being assigned to the Pterosauria, a group that includes the first vertebrates to develop active flight. The original Faxinalipterus fossil consisted of bones from the postcranial skeleton and part of the skull (an upper jaw with several teeth), found separately during two field expeditions, conducted in 2002 and 2005, at the site fossil of Linha São Luiz, located in the municipality of Faxinal do Soturno. Thus, it was not possible to say with certainty whether all the parts belonged to the same type of animal and species. Despite this, it was assumed at the time that all the bones belonged to a single species, named Faxinalipterus minimus.

The new study of Faxinalipterus established that there were two distinct species, with the isolated jawbone representing another animal. This was possible based on the comparison with a new fossil recently found at the same site (Linha São Luiz). The new material is composed of an incomplete skull, the maxilla of which presents the same characteristics of the maxilla attributed to Faxinalipterus. Additionally, there are parts of the mandible, scapula, and some vertebrae. The maxilla of Faxinalipterus can therefore be incorporated into the description of the new fossil, named Mahary Bonapartei.

“There has always been great doubt whether the two specimens attributed to Faxinalipterus represent the same species, and whether it was a flying reptile,” commented Alexander Kellner, a pterosaur specialist who currently leads the National Museum/UFRJ. After examining the specimen shortly after its publication in 2010, he found that several bones could be misidentified and the lack of diagnostic features of pterosaurs, including the lack of specific features on the humerus (forelimb bone ), as a broad, projecting deltopectoral crest, which is typical of pterosaurs. Borja Holgado, also a specialist in pterosaurs from the Catalan Institute of Paleontology and currently a researcher at the Regional University of Cariri (Ceará), analyzed the material and approved the first conclusions. “It was clear to me that it is a primitive reptile that did not belong to the pterosaurs, since it did not present any unambiguous characteristic of this lineage” explained Holgado and underlined: “But the current knowledge of the faunas at the end of the Triassic indicates that the disparity of animals at this time was so great that animals that might look like pterosaurs at first sight, but in reality are not flying reptiles. Faxinalipterus and Maehary.

“The material on which Faxinalipterus is based is very fragile and very incomplete. In addition, parts of the bones were covered with rock matrix, which required more detailed preparation” commented Cesar Schultz, from the UFRGS and one from the authors of the 2010 work and the new research that has just been published.

The preparation of the original material required a lot of experience and was carried out in the National Museum. “Fortunately, we were able to photograph the entire specimen in great detail,” said Orlando Grillo, who took care to reproduce in drawing form every anatomical detail of the Faxinalipterus bones.

It was with the help of a scanner that the enigma was revealed. “Computed tomography is a tool that is increasingly used in paleontological studies,” emphasizes Ricardo Lopes of COPPE/UFRJ. “It’s a non-destructive analysis that makes it possible to visualize anatomical details still covered by the sedimentary rock where the fossil is preserved,” adds Olga Araújo, also from COPPE.

“In the original 2010 work, we found that the teeth present in the maxilla of Faxinalipterus were very close together, which is a feature of early Triassic pterosaurs. However, tomography of the maxilla showed that the teeth were not separated as originally thought., as many teeth had been lost during the fossilization process. As a result, the dentition pattern and the close spacing between the alveoli (cavities where the teeth are inserted) were not compatible with pterosaurs”, emphasizes Marina Soares.

After these studies, there was still some doubt about who, after all, was Faxinalipterus. The solution came from the discovery of a new specimen that had been collected from the same region from which the specimens of Faxinalipterus originated. “Systematic collections have been carried out by the CAPPA (Center of Support for Paleontological Research of the Fourth Colony), of the UFSM, revealing a series of new fossil species for the Triassic of Rio Grande do Sul”, commented Flávio Pretto . In the Linha de São Luiz fossil site, in the municipality of Faxinal do Soturno, several fossils have already been found, such as close relatives of mammals, dinosaurs and other reptiles. The area where the excavations were carried out is located in the territory of the Quatro Colônia — which is seeking to become a UNESCO Geopark.

“When we had access to the study being compiled by the National Museum team, it became clear that the maxilla, hitherto called Faxinalipterus, was very similar to the material we were studying,” Leonardo added. Kerber. “These were definitely not examples of pterosaurs,” reinforced UNIPAMPA’s Felipe Pinheiro, a researcher who is also an expert on winged reptiles.

Using an anatomical database, the team established that Faxinalipterus would be closely related to lagerpetids, a branch thought to be a sister group to Pterosauria in more recent studies. Together the lagerpetids and pterosaurs form a larger group called Pterosauromorpha. In this context, the new species Maehary bonapartei was positioned as the most primitive member within Pterosauromorpha. “That is, Faxinalipterus and Maehary are not pterosaurs, but are related to them. In particular, Maehary is set up as a key element in elucidating how anatomical features evolved along the lineage of pterosauromorphs to pterosaurs themselves, fully adapted to flight,” says Rodrigo Müller. “These species, estimated at 30cm in length for Faxinalipterus and 40cm in Maehary, demonstrate the importance of continuing to collect fossils in this region.”

The genus name of the new species comes from Ma’ehary, an expression of the original Guarani-Kaiowa people, which means “who looks at the sky” in allusion to its position in the evolutionary line of reptiles, being the most primitive of the Pterosauromorpha, group that includes the fascinating pterosaurs. The specific name is a fitting tribute to the main researcher of fossil vertebrates in Argentina, José Fernando Bonaparte (1928-2020), who recently died, and who worked actively with Brazilian paleontologists in the outcrops of Rio Grande do Sul, in the collection and description of many extinct vertebrates that lived during the Triassic period, including Faxinalipterus.

Today, researchers are looking for new discoveries that help understand how the earliest forms of this fascinating group of pterosaurs came to be.

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