This is an overview of the of the Eocene Messel Formation as explored by the Messel Pit excavations in Germany. A former quarry and now UNESCO World Heritage Site, the Messel Formation preserves what lived in and around a meromictic lake surrounded by a paratropical rainforest during the latest early to earliest middle Eocene, approximately 47 Ma. A complete list of plant taxa was published in 2024.
Several major monographs on the paleoflora have been published since the early 1900s, with producing the first leaf monograph in 1922, followed by Heidemarie Thiele-Pfeiffer in 1988 who provided the first in-depth palynological revision and expansion. Margaret Collinson, Steven Manchester, and Volker Wilde collaborated to study and redescribe the flowers, fruits, seeds, and other reproductive organs of the formation, with the monograph being published in 2011. Most recently, Johannes Bouchal, Christian Geier, FriÃÂgeir GrÃÂmsson and colleagues have completed monographic studies of the palynomorphs, combining traditional light microscopy with scanning electron microscopy to achieve greater phylogenetic precision.
Only a single dinoflagellate taxon has been described formally from the Messel formation. Based on the predominance in layers where heavy nearshore runoff or slippage is present, its suggested Messelodinium thielepfeifferae was likely an inhabitant of warm nearshore waters in the adult stage or wind and wave action resulted in large accumulation of the cysts. M. thielepfeifferae populations are most prevalent in the older layers of the lake, when it was suggested to be holomictic and become absent in the youngest layers when green algae become dominant with the lake shifting to meromictic conditions and the water chemistry changed.
Olaf Lenz et al (2011) briefly noted the presence of the Zygnemataceae fossil genus Ovoidites, but only gave general population densities with no enumeration on species information.
Several chlorophyte green algae are identified from the Messel Formation, with the greatest concentrations being found in the youngest layers. In the older layers Tetraedron minimum is a distinct component of the yearly varves in the lake, with large blooms occurring to form the lighter summer portions of the varve couplets. In the younger layers, Botryococcus species become the most prolific, having taken over as a major phytoplankton taxon from T. minimum and the dinoflagellate Messelodinium thielepfeifferae.
Carpolitus is a plant morphogenus circumscribed for fossil fruits and seeds that are distinct but not identifiable to defined taxa. Collinson, Manchester, & Wilde (2012) described but did not name 63 distinct Carpolithus morphotypes from the Messel Formation.
The first foray into Messel palynology was produced by H. D. Pflug (1952) with follow-up papers in 1957 and coauthored with P. Thomas in 1953. The pollen and spore record was revised and expanded by Heidemarie Thiele-Pfeiffer (1988) who provided the largest in depth palynological work focusing exclusively on the Messel Formation.