Researchers decode molecular fossils in faeces, exposing prehistoric diets and environments

An international team of scientists, led by Curtin University conducted research on prehistoric droppings. This was done to reveal how the chemical fingerprints of ancient creatures can survive for hundreds of millions of years.

Published in Geobiology, the study examined 300-million-year-old coprolites which is a fossilised feces. These feces were collected mainly from the renowned Mazon Creek site in the United States. These unusual fossils are already known to contain cholesterol derivatives, a strong indicator of a carnivorous diet. The new research, focused on a deeper mystery which is how such fragile molecular traces have managed to withstand the test of time.

• Iron Carbonate: Nature’s Time Capsule

Traditionally, scientists believed that phosphate minerals played the leading role in preserving soft tissues and molecular detail. Yet the team discovered that the true guardians of these biomolecules were tiny grains of iron carbonate, scattered throughout the coprolites. They act like natural micro-capsules. These minerals protected delicate traces of prehistoric life from decay.

• New Perspective on Fossilisation

Dr Madison Tripp, lead author and Adjunct Research Fellow at Curtin’s School of Earth and Planetary Sciences, said the work reshapes our understanding of molecular fossilisation.

“Fossils don’t only capture the outlines of long-extinct creatures—they can also safeguard their chemical signatures,” Dr Tripp explained.

“The puzzle has always been how such fragile molecules endure for hundreds of millions of years. Our findings show that iron carbonate, not phosphate, was the shield keeping these traces intact.”

• Why It Matters

The discovery opens new opportunities for palaeontologists. By understanding which minerals preserve biomolecules, scientists can better identify fossils that may still hold chemical evidence of ancient diets. Their ecosystems and even decomposition processes can help to piece together not just how ancient creatures looked, but how they lived and died.