A new pachypleurosaur from the Early Ladinian Prosanto Formation in the Eastern Alps of Switzerland

作者：Nicole Klein, Heinz Furrer, Iris Ehrbar, Marta Torres Ladeira, Henning Richter, Torsten M. Scheyer · 发表于：Swiss Journal of Palaeontology · 年份：2022 · DOI：10.1186/s13358-022-00254-2 · 被引用次数：14 · 研究领域：Paleontology and Evolutionary Biology、Paleontology and Stratigraphy of Fossils、Evolution and Paleontology Studies

Abstract The Alpine Prosanto Formation (Middle Triassic) cropping out in the Ducan region in eastern Switzerland has yielded a rich fish and reptile fauna. Here, we present new pachypleurosaur remains from the upper part of the formation (Early Ladinian), similar to the previously known pachypleurosaurs from the Middle Triassic UNESCO World Heritage Site of Monte San Giorgio in southern Switzerland/northern Italy. From these remains, a new pachypleurosaur species, Prosantosaurus scheffoldi nov. gen. et spec., is described on the basis of six fairly complete skeletons, one disarticulated specimen and an isolated skull. As is typical for pachypleurosaurs and most other Triassic marine reptiles, the new taxon is based to a large degree on a combination of characters (e.g., nasals articulating broadly with the anterior margins of the prefrontals and lacking posterior processes; postorbitals with rounded anterior processes that articulate with the postfrontals anterolaterally) rather than on many unambiguous autapomorphies, although a few of the latter were found including (1) a premaxilla which is excluded from entering both the external and internal nares and (2) a parietal, which is distinctly longer than wide and carrying distinct anterolaterally angled processes. Phylogenetic relationships of the new taxon are tested within European Pachypleurosauria, revealing that the new species is the sister taxon to a clade including Serpianosaurus , Proneusticosaurus , and the monophyle...