The Öhningen Fossil-Lagerstätte: multi-proxy insights into the preservation of a unique window of Miocene biodiversity

The middle Miocene (c. 14–13 Ma) Öhningen Fossil-Lagerstätte is one of the most famous fossil deposits in Germany and one of the most important Cenozoic deposits worldwide. The Öhningen Fossil-Lagerstätte has been known since the Middle Ages, and the two quarries were already exploited around the year 1500 for building stone and lime. In addition to its abundant plants and vertebrate fauna, the soft-bodied biota preserved in Öhningen is diverse, including various insects, aquatic arthropods, and arachnids. While the Öhningen Fossil-Lagerstätte is often regarded as a single deposit in the literature, it is imperative to recognize that there are notable differences between the two separate outcrops. Not only are there variations in sedimentology, modes of preservation of the soft-bodied fossils, and fossil diversity at the outcrop scale, but these elements can also vary within even a few centimetres of the same exposure. Part of this variation can be attributed to changing depositional environments and seasonality, but modern weathering and historical collections bias may also play significant roles. However, understanding the correlative nature of these proxies is in its infancy. Here we present new data from sedimentological, petrographic, paleontological, and electron microscopy with elemental mapping investigations to showcase the importance of a multi-proxy approach to the understanding of this convoluted deposit. The aim is to provide improved clarity into the paleoecological and taphonomic questions that have plagued Lake Öhningen for decades.