Living conditions in a Lower Triassic playa system of Central Germany: evidence from ichnofauna and body fossils

Trace fossils and body fossils are described and interpreted from a red-bed succession of the Bernburg Formation (Gandarian, Lower Buntsandstein) of the Beesenlaublingen Pit (Central Germany). Compared to an abundant ichnofauna, invertebrate and vertebrate remains are generally rather poor with the exception of conchostracans, which can be found in large quantities. In contrast to the lowermost Buntsandstein (basal Calvörde Formation) of the area, the overlying lower Bernburg Formation contains a moderate ichnodiversity with a number of distinct ichnotaxa and shows a rapid increase of continental trace fossils after the end-Permian mass extinction. Most common are Fuersichnus communis and Phycodes curvipalmatum, accompanied by Skolithos verticalis and small spherical traces, probably the product of insect larvae. Furthermore, Cruziana problematica, Rusophycus eutendorfensis, Diplichnites triassicus, Diplopodichnus biformis and Stiallia pilosa could be recognised and are interpreted to be mainly the result of notostracans and conchostracans. Lockeia siliquaria is a resting trace probably made by conchostracans and/or bivalves. Less abundant or rare, and partly enigmatic, trace fossils are ?Tambia spiralis (insect burrows), a complex trace fossil of an arthropod (?), and a spreiten-like burrow of an annelid (?). Elements of the Scoyenia ichnoguild, which are otherwise common in Triassic continental environments, are rare or absent due to the lack of firmground substrate. The interpretation of the ichnofauna is supported by a comparatively abundant arthropod fauna consisting of conchostracans, notostracans and xiphosurans. Based on the sedimentological and palaeontological evidence, the palaeoenvironment of the studied section can be characterised as an ephemeral (playa) lake environment. This study particularly demonstrates the utility of ichnological analysis as a powerful tool in palaeoenvironmental reconstructions especially of playa deposits.