Palaeobotany studies all types of fossilized remains of earth’s vegetation in the geologic past. Macrofossils (e.g., impressions and compressions of leaves, silicified seeds and wood), microfossils (e.g., spores and pollen grains), and, to a lesser extent, trace fossils (e.g., chemical signatures such as isotope ratios) are used to reconstruct the morphology, growth habit, and, if possible, internal anatomy and physiology of ancient plants. This data represents the basis for our understanding of the systematic affinities, paleogeographic distribution, geologic range, and evolutionary history of the plants, and provides a framework with which plant biodiversity as well as life cycle and community dynamics can be evaluated in ancient ecosystems. Moreover, plant fossils contain direct and indirect information about adaptations or responses of ancient plants to extrinsic factors such as paleoatmospheric CO2 concentration, water availability, phytopathogenic microorganisms, and herbivory, and hence are used as proxy indicators in the reconstruction of ancient ecosystem functioning and climate.
Paleobotanical research in Munich currently focuses on microorganisms as a driving force in terrestrial plant evolution. Fossil microorganisms (e.g., fungi and cyanobacteria) preserved in situ in cherts often display complex associations and interactions with land plants in late Paleozoic (Devonian and Carboniferous) continental ecosystems. We use these fossil communities to detail the biological interactions between different types of microorganisms and between microorganisms and land plants in order to trace co-evolutionary processes and to understand the level of interrelationships in ancient ecosystems.