Isolated marine reptile teeth from the Lower Jurassic Posidonia Shale Formation of Schandelah, northern Germany – Description, classification and implications for biodiversity

The author presents a detailed description and depiction of 13 tooth morphotypes, based on isolated marine reptile teeth from the Lower Toarcian Posidonia Shale Formation (PSF) of Schandelah, Lower Saxony, northern Germany. These morphotypes are compared to selected reference specimens from the collections of the Staatliches Museum für Naturkunde, Stuttgart, Germany, as well as the Staatliches Naturhistorisches Museum, Braunschweig, Germany, with the purpose of systematic assignment. This comparison process shows that most of the isolated teeth belong to thalattosuchian crocodylomorphs, which is surprising, as most non-tooth marine reptile fossils from the Schandelah quarry belong to ichthyosaurians. Even with this disparity in tooth distribution between morphotypes, the isolated teeth can be assigned to all five ichthyosaur genera (Stenopterygius, Hauffiopteryx, Eurhinosaurus, Temnodontosaurus, and Suevoleviathan) known from the PSF, three thalattosuchians (Macrospondylus bollensis, Pelagosaurus typus, and Mystriosaurus laurillardi), and tentatively one pliosauroid (Rhomaleosaurus zetlandicus). Stratigraphic distribution of the isolated teeth points to all groups of marine reptiles having been present throughout the entire section of the PSF exposed at the Schandelah quarry. The thalattosuchian teeth yield the most reliable data on stratigraphic range, as they make up the bulk of all isolated teeth. Finally, new additions to the north German PSF faunal assemblage can be made, as certain tooth morphotypes are the first evidence for the presence of the ichthyosaurian genus Suevoleviathan, the thalattosuchian M. laurillardi, and the pliosauroid R. zetlandicus.