Brazilian 113‑million‑year‑old pterosaur fossil reveals new preservation mechanism

An international team of researchers from Brazil, Australia, Germany and the United States identified a novel global fossilisation mechanism in a 113‑million‑year‑old pterosaur from the Romualdo Formation of the Araripe Basin, Ceará, Brazil. Advanced geochemical, microscopic and 3‑D tomography analyses showed that sulfur‑oxidising bacteria created micro‑environments that rapidly precipitated sulfates, phosphates and carbonates, sealing soft tissues, collagen‑like fibres and even fragile steroid molecules.

The discovery, involving 15 institutions, is the first to detect steroid biomarkers in a pterosaur, indicating a diet of fish and cephalopods. Paleontologist Alexander Kellner described the specimen as “a true time capsule”, while geochemist Klitin Grici called it a “new window on fossil formation”. The findings, published in iScience on 18 June 2026, reshape understanding of how exceptional fossils are preserved and underscore the scientific significance of the Araripe Basin.