MOLECULAR BIOMARKERS IN COPROLITES ILLUMINATE DIETARY INTERACTIONS IN THE CARBONIFEROUS MAZON CREEK ECOSYSTEM

Summary Carbonate concretions are formed under unique conditions which result in exceptional preservation of organic matter through geological time. Coprolite fossils (diagenetically mineralised faeces) preserved in Mazon Creek Carboniferous (306 Ma) concretions have been analysed here using a biomarker approach for the first time, combined with carbon isotopes and multivariate statistical analysis of in-situ Raman spectroscopy data, providing insight into the diet of the producer species in the days before faecal deposition. The C27 steranes in the fossil portions of each concretion comprise greater than 95% of the total steranes, while the matrix portions have a lower overall abundance of steranes, demonstrating that the sterane distribution of the fossils represents the diet of the coprolite producer. Therefore, it is interpreted that the diet of the producer consisted of primarily animal material, suggesting a carnivorous diet, although an omnivorous diet also cannot be ruled out. Biomarkers combined with carbon isotopes here show the potential to distinguish carnivores and omnivores from herbivores in Carboniferous coprolites.