Overview

• A peer-reviewed Geobiology paper published September 19, 2025 reports that microscopic iron carbonate grains shielded delicate biomolecules in coprolites roughly 300 million years old.
• The team analyzed specimens mostly from the Mazon Creek site in Illinois, where the coprolites were already known to contain cholesterol derivatives indicating a meat-based diet.
• Phosphate minerals were linked to preserving fossil structure but were not the agents protecting molecular traces in the studied samples.
• Researchers extended the work to diverse fossils across species, environments, and time periods and observed the same carbonate–biomolecule association.
• The authors say mineralogical criteria can now steer fieldwork and laboratory analyses to recover molecular evidence of ancient diets and ecosystems more efficiently.