Meiobenthic Trace Fossils as Keys to the Taphonomic History of Shallow-Marine Epicontinental Carbonates

An abundant and diverse ichnofauna in Middle Triassic (Muschelkalk) carbonates of the Germanic Basin has been the subject of numerous studies for the past two centuries. Besides the occurrence of numerous macroscopic invertebrate burrow and bioerosion trace fossils, meiobenthic trace fossils are common on micritic bedding planes in Middle Triassic marginalmarine carbonates of the Germanic Muschelkalk Basin. Their rapidly changing style of preservation together with the sedimentological context implies a peritidal (subtidal to supratidal) palaeoenvironment, in which most animals die on an exposed carbonate mud flat due to desiccation and sudden changes in substrate consistency. The uniqueness of this Fossil-Lagerstätte is the fact that many of the soft parts of the meiobenthic trace makers are preserved in situ due to favorable circumstances in which the fossilization of the decaying organic material takes place in a dysaerobic microenvironment after rapid burial. Even if the internal structure of the soft-bodied organisms is mostly destroyed due to early-diagenetic pyrite replacement, their morphology and size can be used to recognize higher taxa and as fingerprints to link a trace maker to a distinct meiobenthic trace fossil. The study of meiobenthic trace fossils is a new approach to solve multidisciplinary problems in ichnotaxonomy, taphonomy, palaeobiology, sedimentology, diagenesis, and sequence stratigraphy.