Pleistocene insular Proboscidea of the Eastern Mediterranean: A review and update

Abstract

The Eastern Mediterranean islands, most of which belong to the Aegean archipelago, have a complex biogeographic history, which puts its stamp on their fauna and flora. A now extinct but most important faunal component, in terms of geographic spread and taxonomic diversity, are the elephants. The Eastern Mediterranean islands are particularly rich in Pleistocene endemic elephant localities, which preserve samples of extinct endemic populations. These were either descendants of the European straight-tusked elephant Palaeoloxodon antiquus or the Southern mammoth, Mammuthus meridionalis. Their presence, history and palaeobiogeography has been documented only for Cyprus, Crete, Kasos, Rhodes, Tilos, Kýthera, Naxos, and Delos. For six other islands only anecdotal references exist in the literature: Kálymnos, Astypálaia, Milos, Sériphos, Kýthnos and Paros. Here, we provide an update on previously published specimens and taxa, describe previously undescribed specimens that were relocated in museum collections, as well as recently excavated specimens, and put these in the context of island palaeobiogeography. We conclude that dwarf elephants, endemic to their palaeo-island, lived on the islands of palaeo-Cyclades, Astypálaia, Crete, Kasos–Kárpathos–Saría, Tilos, Rhodes and Cyprus, whereas the elephants from Kephallenía, Kálymnos and Kýthera are indistinguishable on the species level from mainland Palaeoloxodon antiquus. Elephant fossils of unresolved taxonomic status are reported from five present-day islands. The Eastern Mediterranean endemic elephants likely derived from separate and independent colonisation events from the mainland. No island supported more than one proboscidean species at any time. We found that isolation had no effect on the degree of dwarfism, but that there exists a threshold of about 6–10 km distance between the island and the mainland, below which no dwarfism evolved, likely as a result of genetic contact with the mainland population. We also found that although island area is correlated with the degree of dwarfism in elephants, other factors, such as the level of interspecific competition, may limit this degree.