Format: ORAL

Evelyn Kustatscher Johanna H. A.van Konijnenburg van Cittert2

1Naturmuseum Südtirol, Bolzano, Italy; email: Evelyn.Kustatscher@naturmuseum.it 2Laboratory of Palaeobotany and Palynology, Utrecht, The Netherlands; email: j.h.a.vankonijnenburg@bio.uu.nl

The Triassic was characterized by greenhouse conditions, but experienced major environmental changes linked to several short but severe climate shifts. It is in this climatic scenario that a vegetation turnover took place with the appearance and radiation of modern plant families and the rapid diversification of the gymnosperms, which then became ecologically dominant for most of the Mesozoic era. In 1999 a rich fossil horizon has been discovered within the Anisian terrigenous-carbonatic succession of Khwiesenkopf / Monte Pr della Vacca (Dolomites, N-Italy). The fossil horizon yielded abundant marine fossils, such as brachiopods, bivalves, fishes, and ammonoids, but yielded also abundant terrestrial plant fossils and a small reptile skeleton called Megachirella wachtleri Renesto et Posenato, 2002, which represents the oldest known squamate. The main fossiliferous level represents a rapid burial event caused by submarine flows within a marine basin, triggered by heavy storm events in the terrestrial domain, but plant debris and scattered plant remains occur in other layers along the section as well. The flora is composed of both sterile (shoots, roots, stems, leaves) and fertile organs (fructifications, seeds, fertile fern leaves) attributed to at least 35 taxa. Among those are some of the oldest representants of the Caytoniales seed ferns as well as conifers that are more closely related to the Permian forms than to Mesozoic ones. This demonstrates how this period of time was important for the evolution of plants.