Taxonomy, phylogeny, palaeobiology, and taphonomy of the Pachypleurosauria (Reptilia: Sauropterygia) from the Lower Muschelkalk of Winterswijk, NL

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The Winterswijk quarry (Lower Muschelkalk) in the eastern Netherlands is probably the most interesting Muschelkalk outcrop today, as far as vertebrate fossils are concerned. In addition to the extremely common and well preserved tracks and trackways of terrestrial reptiles, it is yielding an ever increasing amount of partially articulated skeletons of marine reptiles, in particular sauropterygians (pachypleurosaurs and nothosaurs). These forms are known from isolated bones only in other Muschelkalk outcrops. The current project, which is part of a larger Dutch-German joint effort, will focus on the pachypleurosaurs, the most abundant vertebrate body fossils in Winterswijk. The Winterswijk pachypleurosaurs are of particular interest because of their early geological occurrence and because they provide abundant material of otherwise poorly known taxa. Specifically, we want to work out the morphology and alpha taxonomy of the probably two species of pachypleurosaurs present (Anarosaurus heterodontus and Dactylosaurus sp.), put them into a phylogenetic framework, study their ontogeny, their life history (using bone histology), and ultimately their evolution and that of the entire group. The final aspect of the project will be the formulation and testing of hypothesis to explain the highly unusual taphonomy of the Winterswijk quarry.