A remarkably preserved pterosaur fossil from northeastern Brazil has yielded the first molecular evidence ever recovered from one of these extinct flying reptiles. The discovery includes rare steroids that may reveal what the animal ate while shedding new light on the processes that preserved the fossil for 113 million years.
An international team led by Curtin University analyzed a fossilized wing phalanx that had already stood out for its exceptional three-dimensional preservation. Their investigation uncovered chemical traces that had survived since the Early Cretaceous, marking the first time molecules have been identified in a pterosaur fossil.
Published in iScience, the study also revisits a long-standing idea about fossilization. Instead of oxygen acting only as a destructive force, the researchers found evidence that microbial activity linked to oxidative processes may have helped preserve both the fossil’s structure and its molecular signatures.
Rare Molecules Reveal the Pterosaur’s Diet
The researchers identified preserved steroids, an exceptionally rare finding in fossils of this age. Curtin University described the discovery as the first molecular evidence ever recovered from a pterosaur.
Lead author Professor Kliti Grice, John Curtin Distinguished Professor and founding Director of the Western Australian Organic and Isotope Geochemistry Centre, called the specimen “a true time capsule.”
“This fossil is a true time capsule — not only is it beautifully preserved, but for the first time we’ve detected traces of steroids in a pterosaur, providing further evidence that these creatures likely fed on fish or squid,” Professor Grice said.
The study 01574-9?returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2589004226015749%3Fshowall%3Dtrue)also highlights the value of molecular paleontology. By preserving chemical compounds alongside fossilized bone_, the specimen provides another way to investigate extinct animals and the environments in which they lived.
Ancient Microbes Helped Preserve the Fossil
The team’s work also explored how it retained such an extraordinary level of preservationover more than 100 million years. After the pterosaur died and settled on the seafloor, microbes began breaking down its soft tissues and fats, Professor Grice explained. Among them were sulfur-oxidizing bacteria, whose activity triggered mineralization around the body.
That process gradually sealed the remains and preserved the remains in exceptional detail. The researchers argue that these findings challenge the long-held assumption that oxygen mainly contributes to the destruction of organic material during fossilization.
“Rather than being destroyed by oxygen, some fossils are preserved because of it, through oxidative processes carried out by ancient microbiomes,” he noted.
Microbial activity, local chemistry, and the surrounding marine environment worked together to preserve both the specimen’s structure and its chemical signatures.
A New Way to Explain Fossil Preservation
Pterosaurs were the first known vertebrates to achieve powered flight and lived alongside the dinosaurs. Some species reached wingspans of up to 12 meters, while their hollow bones, similar to those of modern birds, could improve the chances of exceptional preservation when environmental conditions were favorable.
The researchers say the newly identified preservation pathway may also help explain similar discoveries at other sites. Professor Grice noted that the findings add to growing evidence that microorganisms played an important role in the survival of ancient fossils.
The study also suggests this process may represent a new global Lagerstätten mechanism, describing the special conditions that allow exceptionally preserved fossils to form.
