Conclusions

Composite imaging enhances the documentation possibilities for lithographic limestone fossils. Composite imaging can be applied under normal light and fluorescence settings. UV fluorescence exhibits the best contrast between the fossil and its matrix. Fossils not showing good UV fluorescence may show green-orange fluorescence. This finding is new and holds true for fossils from Zandt and from Lebanon. Especially for fossils from Lebanon, green-orange fluorescence makes structures visible that are completely invisible under normal light. Composite images can be further combined to optimise the visualisation of specimens, e.g., by combining several lighting methods or combining the part and counterpart.

3D information from specimens from the lithographic limestones can be documented, too. Stereo images and further processing via Structure from Motion appears to be promising. Fluorescing specimens can be documented, or at least small details from them, with cLSM. X-ray tomography appears to be possible in principle, but resolution is at the moment still limited.

EDX element analysis indicates that fossils contain phosphorus; whether this is correlated to the fluorescence capacities of the fossil remains unclear at the moment. The presented method will be used to further investigate small specimens in particular from the lithographic limestones.