DIETARY BIOMARKERS PRESERVED IN CARBONIFEROUS MAZON CREEK COPROLITE FOSSILS
In this study, lipid biomarker analysis, including stable carbon isotope distributions, and multivariate statistical analysis of in-situ Raman spectroscopy data were combined to analyse two coprolites preserved in Mazon Creek concretions in search of ancient dietary insights. The oldest lipid biomarker and isotopic data obtained from coprolites is presented here and used to determine if the animal, which produced these coprolites, was a herbivore, carnivore or omnivore, offering a new perspective to reconstructing ancient trophic networks.
An exceptionally high abundance of C27 ααα 20R cholestane was present in the fossil of each coprolite, with C27 cholestanes and diacholestanes comprising over 95% of the total steranes content. In contrast the concretion surrounding the fossil showed a much lower abundance of overall steranes. It is interpreted that the steranes distribution of each coprolite fossil likely represents the preserved diet of the coprolite producer. The vast majority of animals are understood to produce exclusively C27 sterols, while higher plants produce primarily C29 sterols. In these coprolites therefore, an overwhelming abundance of C27 steranes and lack of C29 steranes suggests a strong input from animal material with little to no input evident from plants, suggesting that the diets of these animals were carnivorous, or potentially omnivorous.