Element mapping by µXRF in several morphotype of Lower Cretaceous coprolites from the French locality of Angeac.

Description

Hundreds of coprolites were found in the Lower Cretaceous locality of Angeac in the Southwest of France, alongside thousands of bones and teeth from dozens of species, encompassing several dinosaurs, crocodilomorphs, turtles and fish (Rozada et al., 2021). Previous studies showed that coprolites can preserve insect remains with great details still intact (Qvarnström et al., 2021). This project focuses on the chemical composition of the coprolites to assess its primary origin and determine the variability between the several morphotypes determined in the locality.
First results show that among the major element, Calcium and Phosphorus dominate the relative composition, followed by Iron and Sulphur. For the minor elements, Cerium followed by Yttrium and Strontium present higher concentration in most coprolites.
Elementary µXRF maps show that, except for Calcium and Phosphorus, those elements are most of the time more concentrated on the outer rim of the coprolites or in inclusions within.
Comparison with surrounding sediments shows coprolites are more enriched of those elements except for Fe and S highly concentrated in pyrite crystals. All those observations strongly suggest a diagenetic origin, by precipitation of fluids inside the coprolites or by conduction with their surfaces.
Further work will focus on the analyse of the oxygen isotopic composition of those coprolites. The aim is to assess if the signal is altered or can be used for paleoenvironment and paleoclimatic reconstruction. Such new proxy is very valuable as coprolites could be used instead of teeth and bones when they are not present in the locality or in addition to them to reduce the destruction of skeleton material.

Period	7 Nov 2022 → 11 Nov 2022
Event title	6th International Palaeontological Congress
Event type	Conference
Location	Khon Kaen, Thailand
Degree of Recognition	International