Non-marine Rhizocorallium (trace fossil) from the Upper Freshwater Molasse (Upper Miocene) of southern Germany

Oblique, U-shaped spreiten burrows found on top of lenses of argillaceous marl within coarse-clastic fluvial deposits of the Upper Freshwater Molasse are clearly of non-marine origin. They can be classified as Rhizocorallium jenense, a trace fossil which has hitherto been regarded as typical of shallow, high energy marine environments and marine omission surfaces. The non-marine burrows, which were most probably excavated by herbivorous larvae of mayflies (Ephemeridae), thus extend the environmental range of Rhizocorallium, and the occurrence of R. jenense can no longer be taken as an unquestionable indicator of marine conditions.