Ichnology of the Rhätsandstein in the Exter Formation (Triassic), Germany

ABSTRACT

The Exter Formation (‘Rhätsandstein’) of the southwestern Germanic Basin records shallow‐marine to deltaic deposition during the Rhaetian (Late Triassic), providing an important record of marginal‐marine ecosystem dynamics during this interval. Although critical for understanding pre‐extinction ecosystem dynamics, the ichnological record of this interval has been only marginally explored. This study provides new data from three sections near Tübingen, Germany composed of well‐sorted, fine‐ to medium‐grained quartz sandstones exhibiting lenticular to tabular geometry, cross‐stratification and sparse pelitic partings. A low diversity trace fossil assemblage is dominated by Diplocraterion with abundant protrusive and retrusive spreiten, along with Arenicolites , Skolithos and a restricted presence of Lockeia , Gordia, Monocraterion , Palaeophycus , Rhizocorallium, and Rosselia . These trace fossils represent a dominating shallow tiering, suspension‐feeding assemblage. These features indicate repeated colonization under high‐energy marginal‐marine conditions, consistent with deltaic to storm‐dominated shoreface settings. Comparison with other Rhaetian ichnological records indicates that trace fossil distribution was influenced by facies and preservational controls. The studied sections record a well‐oxygenated, high‐energy shallow‐marine ecosystem characteristic of the Rhätsandstein.