Volker Wilde’s research while affiliated with Senckenberg Research Institute and Natural History Museum Frankfurt/M and other places

In this first report on the re-investigation of the Eocene Messel palynoflora using combined light- and scanning electron microscopy, comprising Algae to Vitales, it is shown that this epic paleoflora can still provide new insights into the ancient ecosystem prevailing at that time. Applying this combined single-grain method on the palynomorphs enabled us to identify several new floral elements represented in the palynoflora, as well as to revise previous spore/pollen classifications, resulting in a higher taxonomic resolution of the microflora. So far, we have discovered three different algae remains, 28 spore types, and pollen from seven different gymnosperms and 26 unique angiosperms. Some of the new taxa include Lycopodiaceae, Cycadales, Stratiotes (Hydrocharitaceae), and Poaceae. The spore/pollen flora was compared to the meso/macroflora, revealing the importance of combining meso/macrofossil records with state-of-the-art microfossil analyses for a more holistic representation of the paleoflora. This is reflected in the number of taxa only occurring in the microflora (ten families) versus that of the meso/macroflora (18 families). Comparing the results from this qualitative combined light- and scanning electron microscopy study to classical quantitative light microscopy methods already suggests that the combined method provides a higher diversity of spore/pollen taxa. Still, potential floral newcomers could be missed in such single sample investigations that are otherwise detected in the classic up-trough section analyses.

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.

Peat mosses have been an important part of the lignite forming vegetation in the early Eocene of the Helmstedt Lignite Mining District. Three genera of Sphagnum-type spores can be distinguished: Tripunctisporis, Distancoraesporis and Sphagnumsporites. The distribution of these sphagnoid spores is traced through seven lignite seams including most of the known hyperthermal events from the PETM to the EECO. In general, Sphagnum-type spores increase in importance from base to top in each seam as a result of acidification and nutrient depletion during peat accumulation. The proportion of Tripunctisporis increases from Main Seam to Seam 6. The lower three seams are characterized by assemblages typical for coastal plain swamp forests including tree stumps and charcoal in distinct layers and lenses. The upper seams, in which Tripunctisporis is dominant and woody material is rare, are thin-bedded with charcoal in numerous thin drapes on bedding planes. The palynomorph assemblages here indicate a low growing mainly herbaceous vegetation typical of ombrogenous bogs. The change from topogenous swamp forests to open ombrogenous bogs takes place along with the hyperthermals of the early Eocene from the PETM to the EECO. The change from a swamp forest to a shrub forest in the middle of the Main Seam coincides with the isotope excursion of the PETM. Similar changes in other seams independent of thermal events indicate that thermal events merely amplify changes in vegetation, which are primarily imposed by edaphic constraints. It is rather the rapid accumulation of hyperthermals during the EECO that exerts sufficient environmental stress to fundamentally alter the peat forming vegetation. Sphagnum-type spores from the lower Eocene Schöningen Formation

Citation: Ulrich, S.; Vieira, M.; Coiro, M.; Bouchal, J.M.; Geier, C.; Jacobs, B.F.; Currano, E.D.; Lenz, O.K.; Wilde, V.; Zetter, R.; et al. Origin and Early Evolution of Hydrocharitaceae and the Ancestral Role of Stratiotes. Plants Abstract: The combined morphological features of Stratiotes (Hydrocharitaceae) pollen, observed with light and electron microscopy, make it unique among all angiosperm pollen types and easy to identify. Unfortunately, the plant is (and most likely was) insect-pollinated and produces relatively few pollen grains per flower, contributing to its apparent absence in the paleopalynological record. Here, we present fossil Stratiotes pollen from the Eocene of Germany (Europe) and Kenya (Africa), representing the first reliable pre-Pleistocene pollen records of this genus worldwide and the only fossils of this family discovered so far in Africa. The fossil Stratiotes pollen grains are described and compared to pollen from a single modern species, Stratiotes aloides L. The paleophytogeographic significance and paleoecological aspects of these findings are discussed in relation to the Hydrochari-taceae fossil records and molecular phylogeny, as well as the present-day distribution patterns of its modern genera.

A splinter of charred wood was recovered from late Early Eocene volcanoclastic deposits underlying the lacustrine succession of the Messel-pit near Darmstadt (Hesse, Germany). Well-preserved anatomical details due to charring allow for an attribution of the splinter to the Oleaceae family. Within Oleaceae, the wood shows good agreement with the anatomical structure of recent members of the genera Olea , Chionanthus and Noronhia . However, due to the high variability of structural features within this group of genera, a reliable taxonomic placement is restricted to the monophyletic drupaceous subtribe Oleinae. The Splinter was cut loose from a tree of the local vegetation and charred by effects of the respective phreatomagmatic eruption, even under a low-fire regime. The specimen represents a rare example of a Pre-Quarternary wood that can be related directly to a radiometric age of 48.27–48.11 Ma (±0.22 Ma).

Resinites from middle Cretaceous infillings of karst structures exposed in two limestone quarries in the Rhenish Massif, Germany, were analyzed for their terpenoid biomarker signatures using GC–MS to infer their original plant sources and depositional history. The total solvent extracts of the resinites were composed mostly of mono-, sesqui- and diterpenoids. The predominant compounds in all resinite extracts were diterpenoids derived from the abietane, isopimarane, pimarane, and labdane classes. These resinite compositions are characteristic for conifer resins, thus interpreted as derived from such sources. Based on the mono- and diterpenoid chemistry, alteration of these resinites occurred mainly prior to transportation and final burial. The results show that these terpenoids are excellent molecular markers for the chemosystematic assignment of resinites preserved dissociated from their plant sources.