The Langenberg Quarry in Northern Germany: a peculiar terrestrial Late Jurassic biota in marine limestones

WINGS, OLIVER; ANDRES, BRIAN; CARBALLIDO, J. L.; ET AL

Bonn

Simposio; 13th Symposium on Mesozoic Terrestrial Ecosystems and Biota; 2018

Despite abundant outcrops, terrestrial fossils from Late Jurassic strata in Lower Saxony, Northern Germany, are very rare. This is because the Lower Saxony Basin was covered by a shelf sea that was surrounded by large paleo-islands 150 million years ago. The most outstanding exception to this pattern is the terrestrial fauna and flora found in the Langenberg Quarry near Goslar, a classic outcrop of late Oxfordian to late Kimmeridgian marine limestones and marls at the northern rim of the Harz Mountains in Northern Germany (Wings and Sander, 2012). The quarry is best known as the type locality for the dwarfed basal macronarian sauropod dinosaur Europasaurus holgeri (Sander et al., 2006), but has also yielded remains of numerous other organisms from this Late Jurassic island. Land plants from the Langenberg include twigs and very rare cones of araucarian conifers. Wellpreserved leaf cuticles indicate identification as Pagiophyllum (likely Araucariaceae). Abundant remains of Europasaurus dominate the dinosaur assemblage, which also includes three bones of a diplodocid sauropod (possibly also dwarfed), a stegosaur tooth, very few theropod bones with possible affinities to Ceratosauridae and several theropod teeth. A general survey of more than 80 Late Jurassic theropod teeth from several localities in Northern Germany via a character-based study and a morphometric analysis (discriminant function analysis) indicates that the Late Jurassic islands of Northern Germany provided habitats for a diverse variety of theropod groups including basal Tyrannosauroidea, Allosauroidea, Megalosauroidea cf. Marshosaurus, Megalosauridae cf. Torvosaurus, and probably Ceratosauria (Gerke and Wings, 2016). Europasaurus provides the largest sample size of skull material for an ontogenetic study in any sauropod taxon (Marpmann et al., 2014). The puzzling taphonomy of Europasaurus is unique because the abundant and exquisite three-dimensionally preserved bones ? ranging from disarticulated elements to associated partial skeletons ? were buried in the shallow marine environment. At least 21 Europasaurus individuals belonging to different ontogenetic stages have been identified up to now. The high number of individuals renders taphonomical hypotheses such as drifting carcasses, or swimming or rafting animals implausible. The most parsimonious interpretation is that a herd of Europasaurus migrated within the tidal zone and died during the crossing. About one third of the prepared bones bear marks of smaller scavengers. These probable tooth marks are tentatively assigned to invertebrates, small fish or, less plausibly, crocodilians. Taphonomic research is also benefiting from ongoing studies of the sedimentology and microfacies of the Late Jurassic shallow-water carbonates in Lower Saxony and a high-precision stratigraphic framework based on isotope-geochemical analyses (Zuo et al., 2017). Non-dinosaurian terrestrial vertebrates include 3D-preserved remains of several pterosaurs, a paramacellodid lizard, and the type specimens of the small atoposaurid crocodilian Knoetschkesuchus langenbergensis (Schwarz et al., 2017). Among the 15 pterosaur specimens are four gnathosaurine pterodactyloids, several possible rhamphorhynchid teeth, and the basal-most and oldest member of Eupterodactyloidea. Microvertebrate remains recovered by screen-washing are dominated by fish and crocodilian teeth but also included an astonishing variety of mammal teeth. Multituberculata are represented by several isolated molariform teeth and include the type specimens of Teutonodon langenbergensis (Martin et al., 2016). Langenberg docodonts and dryolestids are the easternmost European representatives of these groups. Docodonts only are represented by indeterminate fragments of molars. Three dryolestid molars exhibit a close relationship to those in the English Purbeck Group. Triconodonta are represented by an eutriconodont molariform with a distinct cingulum. Dinosaur tracks discovered stratigraphically only five meters above the Europasaurus-bearing layer are the earliest unequivocal evidence for emergence in the Langenberg section, indicating a sea level fall (Lallensack et al., 2015). The tracks were produced by theropod dinosaurs larger than any animal known from the dwarfed island fauna, indicating a faunal interchange ≤ 35,000 years after the Europasaurus bone accumulation (Lallensack et al., 2015). The Langenberg discoveries provide unique insights into a Jurassic European insular ecosystem and close a significant gap in our knowledge of early mammal evolution. Paleobiogeographically, close relationships to the contemporaneous Guimarota (Portugal) vertebrates exist. This is not only true for the mammals, especially the multituberculates, but also for Knoetschkesuchus langenbergensis, which is closely related to K. guimarotae, and for the basal scincomorph lizard that shows close affinities to the Guimarota paramacellodids.