Chronological and Paleogeographical Background to the Study of Oreopithecus bambolii

Oreopithecus bambolii belongs to a unique faunal assemblage found only in Tuscany. Six localities have yiclded specimens of this Maremma Local Fauna, which at Baccinello can be seen to occur in two horizons: V2, dated to about 8·5 Ma, and the older V1. The Casteani faunule corresponds to the latter, while Monte Bamboli (type locality of O. Bambolii) is similar to V2. Updated faunal lists for the two horizons are provided. Several rodents and a charophyte indicate European affinities for part of the assemblage, while two bovids and Oreopithecus are of African origin. Although the paucity of species (especially carnivores) and the presence of "giant" rodents suggested an insular environment to Hürzeler and Engesser, the lack of any concomitant reduction in size of the large mammals does not support this view. Faunal and floral considerations indicate that although open country may have occurred nearby, Oreopithecus probably inhabited a swampy forest. Analysis of the regional paleogeography suggests that a tectonically folded passageway may have permitted the one-way "filter-bridge" migration of terrestrial mammals from northern Africa and from continental Europe into Tuscany, but probably at different times.