Magnetostratigraphy of the Late Miocene Baccinello-Cinigiano basin (Tuscany, Italy) and the age of Oreopithecus bambolii faunal assemblages

摘要

This study has the aim of dating the latest Miocene Hominoid Oreopithecus bambolii bearing succession of the Baccinello-Cinigiano Basin (BCB) in southern Tuscany (Italy). Since the 1960s biochronology has been the source for rough age estimations. Geochronological techniques have started to provide significant time constraints after the absolute dating obtained from a single point in the BCB, where a relatively thick and continuous lithostratigraphic record is found together with a succession of several mammal sites. Chronological control of the sedimentary succession and age range of Oreopithecus faunal assemblage has nowadays only been possible with the characterization of the magnetostratigraphy of the BCB sedimentary succession. This study demonstrates that: i) the oldest Oreopithecus bearing sediments in BCB (V1) has an age older than 8.1. Ma; ii) the IGF 4883V Oreopithecus from Trasubbie creek has an age of 8.1-7.7. Ma; iii) the youngest Oreopithecus remains (from the so called V2 assemblages) have an age between 7.1 and 6.7. Ma; iv) the Oreopithecus chronologic range within the BCB is about 1.5. Ma long bracketed between 8.3 and 6.7. Ma; v) the post-. Oreopithecus faunal complex V3-bearing deposits, likely to have an age between 6.7 and 6.4. Ma, belonging to the very early MN13 unit (early Messinian); and finally, vi) Oreopithecus is confirmed to be the youngest dryopithecine record from Eurasia, extending his last occurrence into the early Messinian.