A large osteoderm-bearing rib from the Upper Triassic Kössen Formation (Norian/Rhaetian) of eastern Switzerland

Torsten M Scheyer; Urs Oberli; Nicole Klein; Heinz Furrer

doi:10.1186/s13358-022-00244-4

A large osteoderm-bearing rib from the Upper Triassic Kössen Formation (Norian/Rhaetian) of eastern Switzerland

Swiss J Palaeontol. 2022;141(1):1. doi: 10.1186/s13358-022-00244-4. Epub 2022 Feb 23.

Authors

Torsten M Scheyer¹, Urs Oberli², Nicole Klein¹, Heinz Furrer¹

Affiliations

¹ Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland.
² Waldgutstrasse 21, CH-9010 St.Gallen, Switzerland.

Abstract

An important component of the Alpine vertebrate record of Late Triassic age derives from the Kössen Formation, which crops out extensively in the eastern Alps. Here, we present an isolated and only partially preserved large rib, which carries an osteoderm on a low uncinate process. Osteological comparison indicates that the specimen likely belongs to a small clade of marine reptiles, Saurosphargidae. Members of the clade are restricted to the western (today Europe) and eastern margins of the Tethys (today China) and were so far known only from the Anisian stage of the Middle Triassic. The assignment of the new find to cf. Saurosphargidae, with potential affinities to the genus Largocephalosaurus from the Guanling Formation of Yunnan and Guizhou Provinces, China, would extend the occurrence of the clade about 35 million years into the Late Triassic.

Keywords: Late Triassic; Osteoderm; Osteology; Palaeobiogeography; Sauropterygia; Saurosphargidae; Tethys Ocean.