New research work on the palaeoenvironment and biota of the late middle Permian Hornburg Formation, central Germany

A series of excavations in the fossiliferous Blätterton Member of the Hornburg-Formation (Eisleben municipality, Saxony-Anhalt) was carried out between 2022 and 2024 by an international team of scientists, students and volunteers on an area of about 60 m² and covering a thickness of 4.5 meters. The fieldwork included a finestratigraphic documentation and yielded a vast amount of trace fossils – about 2000 specimens that were collected with exact assignment to lithological units; it expanded our knowledge about a crucial middle Permian ichnofauna. The Blätterton Member is dominated by silt- and claystones with some intercalation of laterally tapering bodies of standstone; it represents a succession that is typical for a playa lake environment. Given the muddy substrates that barely show signs of vegetation cover, footprints of larger herbivores are missing. In this aspect, the Blätterton ichnofauna differs from the somewhat younger Mammendorf assemblage, which is marked by tracks of larger tetrapods including herbivores, plant roots and burrows within predominantly sandy substrates that were deposited in a floodplain environment with steppe-like vegetation cover. In the Blätterton succession, however, relatively small tracks of the type Dromopus are abundant. They were produced by reptiles that likely fed on small arthropods, whose abundance and diversity is testified by mass occurrences of arthropod tracks in addition to aquatic insect larvae preserved as body impressions. A second tetrapod footprint type, tentatively referred to the ichnogenus Capitosauroides, is often associated with swimming traces made by the same producers indicating a lifestyle in proximity to small ponds and shallow water bodies.