Supplementary materials for Chemical characterization of Nannoconus based on synchrotron micro X-ray fluorescence

Nannoconus, a major planktonic carbonate producer in the Early Cretaceous (~150–120 Ma), formed the largeest (size ~5-20 μm) and heaviest (mass ~200-1400 picogram) calcite skeletons, contributing to massive marine carbonate accumulations for ~30 million years, but its calcification site remains unknown. Magnesium (Mg) is a useful indicator of calcification site, as typically extracellular calcite contains more Mg than intracellular calcite. To assess Mg and other elemental content in Nannoconus, a chemical analysis was performed utilizing micro X-ray fluorescence (μ-XRF) at the ID21 beamline of the European Synchrotron Radiation Facility (ESRF). The results of this experiment are planned to be submitted as a publication in the journal of PCI Paleontology with the title of: Chemical characterization of Nannoconus based on synchrotron micro X-ray fluorescence. This dataset contains the supplementary images, tables and python-based code documented in the manuscript.