Isoleucine epimerization ages of quaternary mammals from Sicily

Abstract

Isoleucine epimerization ages of 48 fossil mammal samples taken from cave, coastal plain and marine deposits in three areas in Sicily fall in two significantly different relative age groups, i.e. about 455±90 and 200±40 Ka, respectively. The D-alloisoleucine/L-isoleudne (alle/ile) ratio was measured in the tooth enamel of Elephas cfr. antiquus, E. mnaidriensis Adams, E. falconeri Busck, Hippopotamus pentlandi Meyer, Cervus Sicifiae Pohlig and Praemegaceros carburangelensis (De Gregorio), and come from the best known sites of mammal fossils in Sicily, i.e. the Peloritani-Nebrodi chain, the Iblean Plateau, and the Palermo mountains. E. falconeri, which has been considered as the youngest Sicilian elephant since the time when Vaufrey studied this dwarf species (Vaufrey 1929), falls actually in the older relative age group. The epimerization ratios for the medium-sized species of the Elephas genus (E. mnaidriensis) fall in both the two relative age groups. Conversely, the ratios obtained for the Hippopotamus pentlandi samples fit only to the younger group. E. mnaidriensis from the older group is associated with E. falconeri and with other typically endemic species. The E. mnaidriensis samples from the younger group, are associated with hippos as well as with cervids, bovids and carnivores. The obtained epimerization ratios support the assumption that Sicily experienced at least two elephant immigrations in Pleistocene times, and also suggest that a very thorough review of the remains of E. mnaidriensis may lead to a discrimination of separate species of this medium-sized elephant in each of the two relative-age groups.