Millions of reptile tracks—Early to Middle Triassic carbonate tidal flat migration bridges of Central Europe—reptile immigration into the Germanic Basin

Abstract

Discoveries of vertebrate track sites in Central Europe have occurred in 75 localities in carbonate tidal flats of the Middle Triassic. In the Germanic Basin carbonate tidal flats were wide-span mapped, resulting in the finding of millions of small- to medium-sized reptile tracks. In the west of the basin the sediment of the Lower Muschelkalk to basal Upper Muschelkalk contains at least 21 track horizons, whereas in the eastern part more typically marine conditions were present. Here, tidal flats with additional track beds started earlier during the Upper Bunter and demonstrated marine ingression from the eastern Silesian gate. During low stands these tidal flats comprised inter-peninsula bridges, which allowed migration of reptiles. Only two medium to small prolacertilian reptiles, which were fully adapted to these environments, left any kind of track. A large thecodont reptile such as Euparkeria was the potential predator that may rarely have hunted the main small trackmakers Macrocnemus and Hescherleria.