Vertebrate track bed stratigraphy at new megatrack sites in the Upper Wellenkalk Member and orbicularis Member (Muschelkalk, Middle Triassic) in carbonate tidal flat environments of the western Germanic Basin

This article examines the high-resolution track horizon and track bed stratigraphy at two new Middle Triassic megatrack sites in NW Germany. The first megatrack site consists of the localities Hagen and Detmold and spans over a distance of about 30 km in the Upper Wellenkalk Member of the uppermost Lower Muschelkalk (Pelsonian). The second megatrack site was found between Niederlistingen and Ostheim over a distance of 10 km in the orbicularis Member of the lowermost Middle Muschelkalk (Illyrian). At all track sites the track beds are mud-cracked microbial laminates and yellow dolomites, products of microbial mats in carbonate tidal flat environments. Vertebrate tracks Rhynchosauroides tirolicus Abel, Procolophonichnium haarmuehlensis (Holst, Smit, Veenstra) as well as scratch marks, and Undichna isp. are abundant. Recently 11 track beds have become known from the Upper Roet Member (Upper Bunter) to the Marl/Dolomite Member (Middle Muschelkalk) in the Germanic Basin. Six of these track beds build megatrack sites with an extent of 10–400 km. The result is a completely different picture of the bathymetry during Bithynian to Illyrian in the Germanic Basin, a flatter basin with a surrounding carbonate tidal flat belt changing its position periodically.