Rieppel, O. 1989 A new pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland Philosophical Transactions of the Royal Society of London Series B 323 1-73 Paleothyris Araeoscelis Petrolacosaurus Coelurosauravus Claudiosaurus Youngina Gephyrosaurus Pachypleurosauridae non_pachypleurosaur_Sauropterygia Osteology Maximum Parsimony Based on reanalysis of the original matrix. Rieppel_1989a