Quantitative Dual-Energy CT as a nondestructive tool to identify biosignatures in fossil diapsid and mammalian bones

Dual-energy computed tomography (DECT) is an imaging technique that combines nondestructive morphological cross-sectional imaging of objects and the quantification of their chemical composition. Its potential to assist investigations in palaeontology has not yet been explored. This study investigates quantitative DECT for the nondestructive density- and element-based material decomposition of fossilized bones. DECT was developed and validated here for imaging-based calcium and fluorine quantification in fossil bones of different geological age of Nothosaurus sp., Ichthyosauria indet., Dysalotosaurus lettowvorbecki, Tyrannosaurus rex, Alcelaphinae indet., and an extant Bos taurus. The analysis shows that DECT material maps can differentiate bone from surrounding sediment and reveals fluorine as an imaging biosignature for fossilized bone and a reliable indicator of the age of at least terrestrial living organisms. These findings highlight the relevance of radiological imaging techniques in natural sciences by introducing quantitative DECT imaging as a nondestructive approach for material decomposition in fossilized objects, thereby potentially adding to the toolbox of palaeontological studies.