Format: ORAL

Hans Kerp; Benjamin Bomfleur

Institute of Geology and Palaeontology, University Münster, German

With some 60 species the Umm Irna flora from the Dead Sea region in Jordan ranks among the most late Permian diverse floras known worldwide. During the latest Permian the present-day Dead Sea region was situated at a paleolatitude of c. 15S at the western end of the Paleotethys in a monsoonal floodplain setting with meandering rivers, abandoned channels, ephemeral lakes and backswamps of various size. The Umm Irna Formation, exposed on the eastern side of the Dead Sea, is characterized by rapid vertical and lateral facies changes. About a dozen localities have yielded a very diverse flora reflecting the different depositional settings. Not only the high diversity but also the excellent preservation, particularly the cuticles, and the composition make this flora unique. The Umm Irna flora comprises elements of at least three of the four major floral provinces, Euramerica, Cathaysia and Gondwana. Not only the mixed nature of this flora is of interest, but also the earliest appearances of extinct plant groups traditionally regarded as typically Mesozoic, i.e., corystosperms and bennettitaleans, and the still existing podocarpalean conifers, which became major, some even dominant constituents of early Mesozoic floras. Moreover, the Umm Irna flora includes the last appearances of long-ranging Paleozoic groups, including noeggerathialean progymnosperms, lepidodendrids, as well as lyginopteridalean, callistophytalean and gigantopteridalean pteridosperms, glossopterids, and walchian conifers. The Umm Irna flora contributes to a better understanding of evolution, distribution, extinction and survival patterns in a crucial period in life history, shortly before the largest mass extinction on Earth.