Villafranchian-Galerian mammal faunas transition in South-Western Europe. The case of the late Early Pleistocene mammal fauna of the Frantoio locality, Arda River (Castell'Arquato, Piacenza, Northern Italy)

We investigated the fossil mammal assemblage from the late Early Pleistocene (early Galerian) site of the Arda River. Seven taxa were identified: one carnivore (Ursus dolinensis), five artiodactyls (Sus strozzii, Pseudodama farnetesis, Praemegaceros sp., Bison sp., and Hippopotamus sp.) and one perissodactyl (Stephanorhinus hundsheimensis). The Arda River faunal assemblage includes taxa already present in the Villafranchian, such as Pseudodama and Sus strozzii. The bear U. dolinensis and the bison, a more evolved form than Bison (Eobison), are taxa typical of the beginning of the Galerian mammal age. Paleontological, sedimentological and paleobotanical data point towards the presence of woodlands settled on an alluvial plain with patches of grassland dated around 1.0 Ma. The continental sediments of the Arda River represent one of the first steps of the forming of the alluvial Po valley.