Vertebrate tracksites in the Obernkirchen Sandstone (late Berriasian, Early Cretaceous) of northwest Germany— their stratigraphical, palaeogeographical, palaeoecological, and historical context

Abstract

The northern German Lower Cretaceous Bückeberg Formation yields numerous dinosaur tracksites, some of which have produced material of impressive quality. Stratigraphically, the localities are concentrated in the Obernkirchen Sandstone, a thin subunit within this formation. The Obernkirchen Sandstone represents mainly a sandy barrier to back-barrier and lagoonal setting within a limnic deltaic facies complex, which was deposited during the late Berriasian (Cypridea alta formosa ostracod subzone) in the southeast of the Lower Saxony Basin, northwest Germany. A few tracksites occur more proximally in coeval fluvial deposits. Dinosaur footprint assemblages were left by ornithopods, theropods, sauropods, ankylosaurs, and small, bipedal ornithischians. Other vertebrate tracks are those of turtles and, possibly, crocodilians. Due to the decrease in sandstone quarrying in recent decades, many old tracksites are inaccessible today. Additionally, historical descriptions of the tracks were of highly variable quality and often published in remote and today nearly unobtainable sources. Here we provide a catalogue of 13 tracksites compiled from the literature and some new observations. Of these 13 tracksites, only five are still accessible and currently under study. Descriptions of each locality are provided, with a comprehensive compilation of existing data on lithofacies, stratigraphy, palaeogeography and palaeoecology of the Obernkirchen Sandstone and equivalent strata. A short review of the track-bearing lithofacies assemblage indicates that the outcrop areas have distinctly different facies and environments, and, therefore, track-bearing horizons can only be correlated stratigraphically between adjacent outcrops. For this reason, the identification of a megatracksite in the Obernkirchen Sandstone is currently regarded as premature and uncertain.