From the Middle Triassic of Ducan, Canton Grisons, Switzerland

14th Swiss Geoscience Meeting, Geneva 2016

A new, exceptionally preserved juvenile reptilian fossil (Diapsida) from the Middle Triassic of Ducan, Canton Grisons, Switzerland

Torsten M. Scheyer *, James M. Neenan **, Timea Bodogan *, Heinz Furrer *, & Mathieu Plamondon ***

*Paläontologisches Institut und Museum der Universität Zürich, Karl Schmid-Strasse 4, CH-8006 Zürich ([email protected]) **Oxford University Museum of Natural History, Parks Road, Oxford, OX1 3PW, UK ***EMPA, Center of X-ray Analytics, Überlandstrasse 129, CH-8600 Dübendorf

The Prosanto Formation exposed at the Ducanfurgga near Davos, Canton Grisons, recently gained importance as another Swiss locality yielding outstanding Middle Triassic fossils. Some of the vertebrate faunal elements, including land-dwelling reptiles, marine sauropterygian reptiles, as well as ﬁshes, are similar to those known from the slightly older Besano Formation at the World Heritage Site of Monte San Giorgio, Canton Ticino and Northern Italy, whereas others are novel findings (e.g., Furrer 2009; Fraser and Furrer 2013; Cavin et al. 2013). Here we report on such a new finding; a small diapsid reptile, which is exceptionally preserved and almost completely articulated. The complete skeleton, exposed in ventral view, is less than 20 cm long, and was scanned using computed microtomography to also reveal its dorsal components. The specimen is characterised by a deep skull with a short rostrum, stout cervical ribs, extremely elongated transverse processes of the thoracic vertebrae, a T-shaped interclavicle, a straight humeral shaft, radius and ulna forming a small spatium interosseum, a slightly curved femoral shaft, a very short and broad tail and only two carpal and tarsal ossifications. Because the animal is considered to be a juvenile, the condition of the latter two might still be prone to change during ontogeny. The most outstanding feature of the new reptile, however, is the presence of extensive body armour, including conical osteoderms on the vertebrae and along the thoracic ribs, as well as a row of flat and keeled osteoderms lateral to the gastralia. Preliminary anatomical comparison indicates affinities of the new specimen with the type material of Eusaurosphargis dalsassoi from the Middle Triassic of Besano, Varese Province, Italy (Nosotti and Pinna 2003).

REFERENCES Cavin, L., Furrer, H., & Obrist, C. 2013: New coelacanth material (Sarcopterygii, Actinistia) from the Middle Triassic of eastern Switzerland, and comments on the diversity of post-Palaeozoic coelacanths, Swiss Journal of Geosciences, 106, 161-177. Fraser, N., & Furrer, H. 2013: A new species of Macrocnemus from the Middle Triassic of the eastern Swiss Alps. Swiss Journal of Geosciences, 106, 199- 206. Furrer, H. 2009: So kam der Fisch auf den Berg – Eine Broschüre über die Fossilfunde am Ducan, Bündner Naturmuseum Chur und Paläontologisches Institut und Museum Universität Zürich, 2. aktualisierte Auflage, 32 pp. Nosotti, S., & Rieppel, O. 2003: Eusaurosphargis dalsassoi n. gen n. sp., a new, unusual diapsid reptile from the Middle Triassic of Besano (Lombardy, N Italy). 14th Swiss Geoscience Meeting, Geneva 2016

Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, 31, 3-33.