A taxonomic Gordian Knot – the sauropodomorph diversity in the Germanic Basin during the Late Triassic

The sauropodomorph-bearing localities from the Norian-Rhaetian of Europe have been traditionally interpreted as monospecific, attributing the morphological disparity in Plateosaurus to intraspecific variability. The Norian and Rhaetian stages are currently not chronostratigraphically defined, making comparisons between the different deposition environments cumbersome. However, from the base of the Norian to the Rhaetian, the sizes of sauropodomorphs increase, with small to medium-sized sauropodomorphs found in the oldest layers of the Löwenstein Formation, to larger and more robust-sized sauropodomorphs from the Tübingen Sandstone (Rhaetian). This contribution presents the results of a basin analysis to reconstruct the environmental changes in the Germanic Basin during the Late Triassic, integrating stratigraphy, fossil record and structural geology. The results of this are that during the Carnian, the opening of Meliata, Pindos and Maliac Oceans in Western Pangaea created rift zones on the carbonate platforms. Towards the Norian, the sea-spreading ceased as these southern oceans started to close just before the new rifting of the Neothetys began. The complex fault systems generated an epicontinental sea that separated portions of Europe as an archipelago that fully developed when the Rhaetian Sea occupied the Germanic Basin. Independently, several iterations of specimen-level phylogenetics of sauropodomorphs found that the three specimens that have been traditionally referred to as Plateosaurus are placed at the base of a comb-like arrangement that includes robust forms, such as Schleitheimia and Tuebingosaurus—two sauropodomorphs that have been previously nested within sauropodiformes. The phylogenetic patterns in a comb-like arrangement suggest a combination of vicariance and migration in the archipelago.