Reinvestigating the Messel palynoflora using combined LM and SEM

The dispersed Eocene palynoflora from Messel, Germany, continues to spike interest and provide new insights into the ancient paratropical ecosystem that prevailed in Central Europe at that time. With this revisit of the palynoflora, using combined light- (LM) and scanning electron microscopy (SEM), we aim to conclude the following: (I) if additional spore/pollen types can be discovered, (II) if previously identified spores/pollen can be taxonomically placed with more certainty, (III) how is the composition and species richness of the palynoflora, (IV) what is the proportion between pollen types from zoophilous versus anemophilous angiosperms, (V) how does the palynoflora correlate with the macro- and mesofloras, (VI) is it possible to adjust the vegetation reconstructions based on the revised palynoflora, (VII) do new plant taxa add any relevant data for the paleoclimatic evaluation, and finally (VIII) how does our combined LM/SEM method compare to previous results using classic LM counting. Until now, our ongoing investigation has revealed various new pollen types, especially of angiosperms, adding considerably to the microfloral list of this locality. We have also been able to adjust previous LM-based segregations into single taxons and amend the taxonomic placement of some spore/pollen types. So far, we have discovered three algal palynomorphs, 31 spore types, seven types of gymnosperm pollen, and about 185 angiosperm pollen types in a single sample, adding ⁓45 new pollen types for this locality. When comparing the palynoflora to the meso/macroflora, expectedly, several taxa are present in both records, but many of the spores/pollen do not have representatives in the meso/macroflora and vice versa – indicating the importance of combining micro/meso/macrofloras when reconstructing paleovegetation and evaluating paleoclimate. Considering the angiosperms, pollen from zoophilous plants is more diverse than pollen from anemophilous plants. Vegetation reconstructions and paleoclimate evaluation await further investigation until the palynological work is finished.