MIDDLE PLIOCENE CETACEANS FROM MONTE VOLTRAIO (TUSCANY, ITALY) - BIOSTRATIGRAPHICAL, PALEOECOLOGICAL AND PALEOCLIMATIC OBSERVATIONS

The historic collection of fossil odontocetes (Cetacea) from Monte Vol traio, near Volterra (Tuscany, Italy) has been examined and lithostrat igraphical and biostratigraphical investigations on the find locality have been carried out. The Monte Voltraio outcrop is referred to the M iddle Pliocene, in particular to Globorotalia aemiliana and Discoaster tamalis zones. The odontocete remains are assigned to the families Ko giidae (Kogia pusilla) and Delphinidae (Globicephala? etruriae and two indeterminate specimens which might belong to Hemisyntrachelus and St enella giulii). The Middle Pliocene cetacean fauna from the Mediterran ean basin (Monte Voltraio and Rio Stramonte associations) includes ext inct taxa or extant taxa no longer represented in this basin. The disa ppearance of these taxa may be linked with the Pliocene and/or Quatern ary climatic deteriorations (e.g. the climatic crisis at about 2.6-2.4 MA).