A collaborative team of micropaleontologists, geochemists, and physicists from ISTerre (CNRS/Université Grenoble Alpes), CEREGE, Institut Néel, SOLEIL, and Rutgers University provides new insights into the mechanisms of skeletal formation in Nannoconus, an extinct calcareous microplankton that played a major role in biocalcification in the Cretaceous seas.
For nearly 35 million years, the exoskeletons of this genus have contributed to massive carbonate accumulations on the seafloor, potentially impacting seawater chemistry. Despite their geohistorical importance, the fine-scale skeletal organization and the associated calcification processes have remained largely unresolved.
The Nannoconus cone-shaped exoskeleton consists of an assemblage of micaliths, themselves composed of imbricated calcitic components, but until now their microstructure was not resolved at scales relevant for discussing biomineralization processes. By combining X-ray ptychographic computed tomography (PXCT) on the SWING beamline at the SOLEIL synchrotron with scanning electron microscopy, this study provides the first three-dimensional reconstruction of a Nannoconus micalith at nanometric resolution, below the thickness of its constituent lamellae.
Read more on the SOLEIL website