BEWARE OF THE “WOLF EVENT” - REMARKS ON LARGE MAMMAL DISPERSALS IN EUROPE AND THE LATE VILLAFRANCHIAN FAUNAL TURNOVER

The “Wolf event” is a prominent concept in large mammal biochronology of western Europe. It was defined in the 1980s as an intercontinental “dispersal event”, best represented by the arrival of a “primitive wolf”, Canis etruscus, but also involving other species. The Wolf event denoted the late Villafranchian faunal turnover, first expressed in Italy in the Olivola Faunal Unit. This event was also considered approximately coincident with the Pliocene-Pleistocene boundary adopted prior to 2009 (~1.8 Ma, Gelasian-Calabrian transition), hence indicating important environmental changes and representing a relevant tool for correlation. Whilst it became soon clear that sporadic finds of modern canids (and, to some extent, other species) pre-dated the age assumed for the Wolf event, several authors continued to use the term and to associate it to the late Villafranchian, referring to the “massive expansion” of the species involved, rather than their first appearance in the European fossil record. Several bioevents traditionally included in the Wolf event and others that have been considered to occur later are today already documented in middle Villafranchian faunas. The “Pachycrocuta brevirostris event”, proposed as a replacement term for the Wolf event, based on current evidence would be characterized by the arrival in Europe of the giant hyena P. brevirostris and Panthera gombaszoegensis, and the increase in the documentation of other species traditionally included in the Wolf event. However, this does not correspond to a sharp faunal turnover as traditionally envisioned for the Wolf event and it is possibly heralded in faunas slightly older than Olivola at ~2.0 Ma. In other terms, available evidence highlights the rather diachronic nature of large mammal dispersal occurred in the late middle and early late Villafranchian (late Gelasian, ~2.2–1.8 Ma), pushing to critically evaluate the biochronological, paleoecological, and paleobiogeographical significance of each bioevent. For instance, the arrival of Hippopotamus in Europe is now attested since ~2.2 Ma, documenting an African dispersal of a species linked to humid conditions in a context that is generally deemed to denote the spread of open-adapted faunal elements of mainly Asian affinities