Insular small mammals from Quaternary deposits of Sicily and Flores

This PhD thesis deals with fossil small mammals from Quaternary deposits from Sicily (Italy) and Flores (Indonesia). It is well known that evolutionary dynamics on islands are quite different than on mainland, because of, amongst the others, the shortage of resources, the reduced interspecific competition and predation, the difficultness in reaching/leaving the island. Therefore many species undergo strong size variation, giving rise to phenomena of gigantism (small mammals) or dwarfism, and a variation in the structure of mammalian communities takes place. In this thesis faunal associations of two very different islands have been taken into account, in order to record the difference in the effects that distance from the mainland, area of the island, introduction of new species and time have on small mammals community. Sicily is in fact the largest Mediterranean island and is very close to the mainland, so close that periodically, during low-standing phases of sea level it was connected to Southern Italy and mammals could reach it. Thus the analysis of the material from Isolidda 3 (Trapani), a Middle - Late Pleistocene paleontological site, could record phases of isolation from the mainland, with a very impoverished (only three rodents and one insectivore) and unbalanced fauna, whilst Oriente Cave (Favignana Island) (Late Pleistocene – Holocene) and Cala Mancina Cave (Trapani) (Holocene), two archeological sites, provided evidence of the arrival of small mammals during the LGM or with man. The abundance of the fossil remains collected allowed also the taxonomical and phylogenetical study of the Microtus (Terricola) and Crocidura in Sicily. The study of small mammals of these archeological deposits facilitates, in conjunction with other disciplines, the reconstruction of the palaeo-environment in which Late Paleolithic and Mesolithic people lived . On the other hand, Liang Bua (Flores, Indonesia) (Late Pleistocene – Holocene), the well-known site for the discovery of Homo floresiensis, is located on an oceanic island. It has never been connected to the mainland and the faunal association displays high degrees of endemism, with the presence of three giants rats (Papagomys armandvillei, Papagomys theodorverhoeveni and Spelaeomys florensis), two middle size rats (Paulamys naso and Komodomys rintjanus) and two small rats (Rattus hainaldi and Rattus exulans). Despite the apparent high number of species, the great part of them is strictly related, confirming the long period of isolation. Since Liang Bua represents the richest deposit for many of these species, it was possible to provide an accurate morphometrical description of upper and lower toothrow of the murids. Moreover, it was possible to record the extinction of Spelaeomys florensis, the severe diminution of the other giant rats (P. armandvillei and P. theodorverhoeveni), Paulamys naso and Rattus hainaldi, and the introduction (intentional or accidental) by Neolithic agriculturists of Rattus exulans.