Ancient Pterosaur Wing Bone Preserved by Microbes for 100 Million Years
A 100-million-year-old pterosaur wing bone found in Brazil shows that ancient microbes paradoxically enabled its preservation. By stabilizing the bone structure and protecting organic molecules, this fossil provides rare evidence of the creature's biology and diet through advanced molecular analysis.
Highlights
- •A pterosaur wing bone found in Brazil was preserved for 100 million years inside a carbonate concretion.
- •Microbial activity played a dual role, initially breaking down tissue and subsequently helping to stabilize the fossil.
- •Researchers identified steroid biomarkers in the bone, providing the first such discovery in a pterosaur fossil.
- •Chemical analysis suggests the reptile likely maintained a marine-based diet of fish or squid-like animals.
Over 100 million years ago, a pterosaur—a flying reptile—soared across ancient oceans in pursuit of fish and squid. Today, this prehistoric creature provides a rare glimpse into the distant past thanks to a fossilized wing bone recovered from the Romualdo Formation in the Araripe Basin of northeastern Brazil. Researchers have determined that this specific bone was subjected to a unique series of chemical transformations that paradoxically destroyed and then preserved its structure for over a century of millions of years.
The Science of Microbial Preservation
The discovery is noteworthy because pterosaur bones are typically hollow, thin, and extremely fragile, making them difficult to preserve in the fossil record. This particular specimen was protected within a carbonate concretion—a natural mineral vault that effectively sealed the remains from the surrounding environment shortly after death. Detailed examination revealed that the bone's preservation was likely facilitated by the very process that initiated its decay.
Microbes actively broke down the soft tissues of the creature on the ancient seafloor, but this activity also altered the local sediment chemistry. These conditions encouraged the rapid formation of phosphate minerals, particularly fluorapatite, which stabilized the bone's delicate microscopic features. Furthermore, evidence suggests that sulfur-utilizing bacteria played a pivotal role in creating the chemical environment necessary for this long-term preservation. This interplay between biological decay and geological stabilization transformed the wing bone into a resilient fossil.
Molecular Clues to Ancient Biology
The fossilized structure functioned as a protective barrier, shielding internal components from environmental degradation. Inside, scientists identified organic molecular traces, including steroidal biomarkers known as steranes. To date, this represents the first documented instance of steroid biomarkers being recovered from a pterosaur fossil. These chemical signatures provide profound insights into the creature’s life, as carbon isotope analysis of cholesterol-derived compounds suggests the reptile consumed a marine-based diet, likely focusing on fish or squid.
Additionally, the research identified preserved structures that resemble collagen fibers, the primary protein framework found in bone. Although these proteins have been chemically altered over eons, the geometric patterns remain consistent with those observed in modern-day birds, which share an evolutionary history with these flying reptiles. This finding highlights a significant shift in paleontological methodology: experts are now capable of recovering molecular and chemical fingerprints from ancient specimens alongside physical skeletal remains. As analytical techniques evolve, this approach could potentially unlock hidden biological information, such as ancient DNA fragments, from even more exceptionally preserved fossils of dinosaurs and other prehistoric animals discovered in the future.
