Messiniense: compleja y grave crisis ecologica

Abstract

The «Messinian» is the last stratigraphic stage of the Miocene, lasting between 6.616.5 and 5.3 MaBP. Its redefinition and stratotype designation were problematic in the 1960s, in the frame of the IUGS International Commission on Stratigraphy (ICS) revision works and the Project 110.25 of the International Geological Correlation Program (IGCP) in the following decades. The interpretation of the regional Mediterranean stratigraphic sequence was debated. Many fossil mammal sites in Spain and other peri-Tethic regions, showing relevant events and intercontinental exchanges within that time span, add pressing questions to the essential need of correlating the continental bio,stratigraphic divisions to the marine based stratigraphic scale. Recent discovery of fossil hominids with early evidence of bipedal adaptation in East-and Central Africa with referred ages of nearly 6 MaBP, or more, makes the study of that age still more exciting. In the same time span, major palaeogeographic, geodynamic, palaeoclimatic and palaeoenvironmental events have been dated, that started been investigated 40 years ago also in connection to the late Miocene Mediterranean «Salinity Crisis»: isolation from the Atlantic Ocean, global sea leve1 lowering, continental accretion and orogeny, glaciation and vegetal cover deterioration. Severa1 models of sequenced interactions have been proposed. A comprehensive scenario is here attempted of these major events in the History of Earth and History of Life, with a calibration of nearly hundred thousand years.