Late Early Pleistocene mammal faunas of Italy: Biochronological problems

Abstract

Sharp and important changes in the large mammal assemblages during the Pleistocene of the Italian Peninsula are not clearly recognisable. A progressive and gradual renewal is however recognisable either by the local evolution of preexisting forms or by recurrent immigrations from Africa, Asia or Central Europe. The main faunistic changes are actually due to an amount of distinct bioevents more or less scattered in time. The documentation gap that generally separates two assemblages in biochronological sequences is too often ignored, and induced to consider a plurality sequence of bioevents as grouped into as a single event. The renewal phases are probably related to climatic fluctuations and it is possible to notice accelerations of this phenomenon in occurrence with major climatic crises (the faunal turnover at the "Middle Pliocene" is taken into account). Bearing in mind that the response of single taxa to climatic and environmental variations is neither uniform nor synchronous, it is very difficult to put a limit between two faunistic units. At present it becomes difficult to set a limit between "Villafranchian" and "Galerian" faunas. Initial hypotheses are offered to propose the beginning of a discussion leading to a more precise definition of the Villafranchian/Galerian "Mammal Ages" transition, at least for Italian mammal fauna assemblages.