Pachypleurosaurs (Reptilia: Sauropterygia) from the Lower Muschelkalk, and a review of the Pachypleurosauroidea

Abstract

The type material of all pachypleurosaurs from the lower Muschelkalk is redescribed and pachypleurosaur systematics are reviewed. Three species of lower Muschelkalk pachypleurosaurs are recognized, Anarosaurus pumilio Dames, Anarosaurus heterodontus n. sp., and Dactylosaurus gracilis Gurich. A cladistic analysis based on 50 characters shows Keichousaurus to be the sister-taxon to all other pachypleurosaurs. The genus Neusticosaurus includes four species, N. edwardsii, N. peyeri, N. pusillus, and N. toeplitschi. The stratigraphic and biogeographic relations of pachypleurosaurs indicate that pachypleurosaurs reached the European epicontinental sea (Muschelkalk Basin) by invasion from the east in Anisian times, and that a faunal interchange was possible between the Muschelkalk Basin and the southern Alpine intraplatform basin facies at least during late Anisian and Ladinian times. -from Authors