Possibilities, challenges, and limitations of dinosaur eggshells LA-ICP-MS U–Pb dating based on samples from Provence (Upper Cretaceous, France)

Obtaining accurate chronostratigraphic constraints on continental deposits is challenging, necessitating innovative dating approaches. Here, we investigate the feasibility of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U–Pb dating of dinosaur eggshell fragments from the Late Cretaceous of Provence, France. Preliminary optical, Scanning Electron Microscopy (SEM), and cathodoluminescence (CL) analyses were critical for identifying zones of optimal preservation and mitigating potential diagenetic contamination. Results from two samples attributed to Megaloolithus mamillare and Cairanoolithus dughii yielded ages of 67.4 ± 4.4 Ma (2s, n = 60 ) and 69.5 ± 9.9 (2s, n = 50 ), respectively, broadly consistent with regional stratigraphic markers. Element mapping reveals significant spatial variation in U and Pb concentrations within individual eggshells, with zones of high contamination contrasting with well-preserved cores. The data highlight the crucial role of diagenesis and organic matter in influencing U–Pb system behavior, although it appears to be limited to early diagenesis. While LA-ICP-MS U–Pb dating of dinosaur eggshells presents substantial challenges, this study demonstrates its potential with careful sample selection and nuanced interpretation, paving the way for further refinement and broader application.