A Tetrapod Ichnoassociation from the Middle Triassic (Anisian, Pelsonian) of Northern Italy

Abstract

A new Middle Triassic ichnofauna recovered nearby the town of Tisens (Bozen) in the Adige Valley (Trentino, Northern Italy) is described. A relatively large ichnoassociation, in which various ichnogenera can be recognized, comes from the basal inter-supratidal layers of a mixed carbonate siliciclastic unit of Pelsonian (Middle Anisian) age. Most of the isolated footprints and trackways pertain to lizard-like reptiles referable to Rhyncosauroides and, subordinately, to archosaurian reptiles. In particular, the ichnogenera Rotodactylus, Synaptichnium and Chirotherium have been recognized. Many tracks are at present unidentified; among them a lizard-like morphotype (morphotype A). The site also yelded numerous fossil plant horizons and some scattered vertebrate remains referable to Placodontidae (cf. Placodus gigas). The site shows the continuity in the Pelsonian of the “chirothere ichnofauna” and the dominance of Rhynchosauroides in carbonate, tidal flat environments.

Keywords:

• Anisian
• Pelsonian
• Rhynchosauroides
• Synaptichnium
• Chirotherium

ACKNOWLEDGEMENTS

We wish to sincerely thank S. G. Lucas (New Mexico Museum of Natural Science, Albuquerque) and U. Nicosia (“La Sapienza” University, Rome) for helpful critical remarks. We are also grateful to G. Tichy (Salzburg University) and to P. Mietto (Padova University) who provided helpful comments and to E. Kustatscher (Ferrara University) for the data about the fossil flora. Field work, carried out with the cooperation of P. Ferretti, M. Franceschi, R. Seppi, R. Tomasoni and M. Trentin, was supported by Museo Tridentino di Scienze Naturali (Trento), Natur Museum Südtirol (Bolzano) and Geological Survey of Bolzano Province (Bolzano).