The discovery of soft-bodied impressions of conodont animals provides critical evidence supporting a nektonic lifestyle, while the exact function of conodont elements, only mineralized components, remains debated. The main hypotheses propose that these elements either formed a grasping/shredding apparatus for feeding or served as structural supports for ciliated tentacles involved in food capture or respiration. Here, we applied high-spatial-resolution Raman spectroscopy to characterize the ultrastructure of conodont elements. Spectral analysis reveals a composite composition dominated by carbonate-fluorapatite/fluorapatite and organic matter. By using the G- and D-band signatures of organic matter to discriminate thermal evolution histories, we selected minimally altered conodont elements for Raman spectral mapping. The mapping results suggest that apatite exhibits greater crystallinity and enhanced concentration in the crown region, which is decoupled from growth laminae patterns, favoring a functional interpretation as a grasping/biting apparatus. Nanoscale structural mapping not only clarifies the function of conodont element but also provided additional constraints for utilizing apatite biominerals in conodonts as geochemical proxies to reconstruct deep-time seawater evolution.
 

Raman spectroscopy,Function of conodont,Apatite biomineral