An international research team led by Curtin University has made significant strides in understanding how molecular fossilisation occurs by examining ancient faeces, known as coprolites. This groundbreaking study, published in the journal Geobiology, sheds light on the diets of prehistoric animals and the conditions they lived in over 300 million years ago.
The research focused on coprolites primarily sourced from the Mazon Creek fossil site in the United States. These ancient droppings were previously known to contain cholesterol derivatives, indicative of a meat-based diet. However, the new findings delve deeper into how these fragile molecular traces survived the passage of time.
Typically, soft tissues fossilise through phosphate minerals. This study revealed that the preservation of molecules was actually facilitated by tiny grains of iron carbonate embedded within the coprolites. According to Dr. Madison Tripp, an Adjunct Research Fellow at Curtin’s School of Earth and Planetary Sciences, this discovery redefines the understanding of molecular preservation in fossils.
“Fossils don’t just preserve the shapes of long-extinct creatures — they can also hold chemical traces of life,” Dr. Tripp explained. “But how those delicate molecules survive for hundreds of millions of years has long been a mystery. While we might have expected phosphate minerals to shield these molecules as well, our findings indicate that iron carbonate played a crucial role instead.”
Expanding the Research Horizon
To assess whether the mineral-molecule relationship was unique to the Mazon Creek site, the researchers broadened their analysis to include a diverse array of fossil samples from various species, environments, and time periods. The results showed a consistent pattern across all samples, suggesting that carbonate minerals have historically preserved biological information throughout Earth’s history.
Professor Kliti Grice, Founding Director of Curtin’s WA-Organic and Isotope Geochemistry Centre, stated that the research opens new avenues for fossil exploration. “This isn’t just a one-off or a lucky find; it’s a pattern we are starting to see repeated,” Professor Grice noted. “Understanding which minerals are most likely to preserve ancient biomolecules enables us to target our fossil searches more effectively.”
With this knowledge, scientists can now identify specific geological conditions that increase the likelihood of uncovering molecular evidence of ancient life.
Reconstructing Prehistoric Ecosystems
This study also enhances the ability to reconstruct ecosystems from hundreds of millions of years ago. Professor Grice elaborated, “By revealing how biomolecules are preserved, we gain powerful new tools to build a richer picture of past ecosystems — not just what animals looked like, but also how they lived, interacted, and decomposed.”
The research highlights the potential of coprolites to provide insights that extend far beyond mere physical forms of ancient organisms. It allows scientists to understand the interactions within ecosystems and the biological processes at work during prehistoric times.
This transformative study, titled “Mineralization controls informative biomarker preservation associated with soft part fossilization in deep time,” was funded by the Australian Research Council (ARC) Laureate Fellowship program and various other grants aimed at advancing geological and paleobiological research.
As researchers continue to explore these ancient treasures, they are not only piecing together the history of Earth’s biological past but also enhancing the understanding of life’s resilience over geological timescales. The implications of this work could reshape the narrative of prehistory and offer deeper insights into the evolution of life on Earth.
