The species taxonomy of the sauropodomorph dinosaurs from the Lowenstein Formation (Norian, Late Triassic) of Germany

The species taxonomy of the sauropodomorph dinosaurs from the Lowenstein Formation of Germany is examined. Previous work has classified these into two taxa: Sellosaurus gracilis from a number of localities and the widespread Plateosaurus engelhardti from a single monospecific accumulation in the Lowenstein Formation, near the town of Trossingen. The current hypodigm of Sellosaurus gracilis is found to contain a substantial amount of variation. This includes differences in the dentition, structure of the skull, composition of the sacrum and the structure of the caudal vertebrae and pelvis. This variation was analysed using a specimen-based parsimony analysis of the sauropodomorphs from the Lowenstein Formation. It was found that two discrete taxa comprise the current hypodigm of Sellosaurus. The more common of these two is a plesiomorphic form for which the correct name is Efraasia minor comb. nov. The less common form (which includes the holotype of Sellosaurus gracilis) is found to share a number of synapomorphies with Plateosaurus engelhardti and is placed in this genus as Plateosaurus gracilis.