Reappraisal of the environmental setting and taphonomy of the Trossingen Plateosaurus bonebeds

The Norian Trossingen Plateosaurus bonebeds have piqued the interest of many researchers over the past 100 years. Several investigations took place in the 1910’s to 1930’s excavating over 80 skeletons, but was then left to rest until 2007. In 2007, 2008 and 2010 small excavations took place, resulting in one and a half skeleton of Plateosaurus trossingensis. The depositional environment of the site has had a controversial history with several theories, ranging from a sandy desert to a catastrophic mudflow, to a watering hole with a muddy bottom. In the summer of 2022 an exploratory investigation was performed at the Trossingen site to prepare for large scale excavation in 2023, which will incorporate stratigraphical, sedimentological and taphonomic investigations to further dive into the evolution of the environment and its relation to the fossil remains. Here we present the first results of both the 2022 and 2023 field campaigns with a revised depositional history. The preliminary investigations in 2022 already showed the section is not as homogenous as previously thought and uncovered several structures, most of which not previously recognised, such as: (1) several small channel–like deposits likely of fluvial origin and (2) a carbonate layer with a possible lacustrine origin in the lower beds, (3) large pedogenetic carbonate nodules in the middle beds, and (4) large mudcracks in the upper beds. All these features, together with preliminary taphonomic data from the bones, suggest a potential upwards aridification trend across the entire section.