Effects of insularity on the ecology of Pleistocene dwarf elephants: first insights into the palaeodiets of Palaeoloxodon falconeri and Palaeoloxodon mnaidriensis from Sicily

The fossil record of the Mediterranean islands attests to several cases of insular dwarfism. The extinct large-sized straight-tusked elephant Palaeoloxodon antiquus underwent this process at least twice during the Pleistocene, resulting in the evolution of Palaeoloxodon falconeri (early Middle Pleistocene) and Palaeoloxodon mnaidriensis (late Middle Pleistocene or Late Pleistocene) in Sicily, a rare case of two insular taxa evolving from the same ancestral species independently on the same island. We investigate diet-related dental wear patterns of P. falconeri and P. mnaidriensis from Sicily to test niche occupation hypotheses, comparing more spatially restricted (P. falconeri) to more widely distributed, mainland-like (P. mnaidriensis) insular contexts. Although P. falconeri did not compete with other herbivorous mammals and could have exploited the most nutritious and palatable resources as a browser, dental meso- and microwear patterns suggest a high degree of dietary abrasion. Palaeoloxodon mnaidriensis, which coexisted with other large herbivores and carnivores, also bears dental meso- and microwear patterns indicative of a high intake of abrasive items. A scenario of insular woodiness (i.e. increased woodiness in insular plants), combined with intense exploitation of the limited vegetation due to the absence of predatory pressure, may explain the abrasive dental wear patterns of P. falconeri. The high degree of abrasion observed in the P. mnaidriensis patterns may reflect an adaptation to a grazing diet associated with the expansion of open grasslands during the Late Pleistocene. This indicates that the dwarf elephants of Sicily developed similar dietary adaptations, albeit in response to different ecological conditions.