Relation of Pleistocene Migrations of Pygmy Stegodonts to Island Arc Tectonics in Eastern Indonesia

Abstract

PLEISTOCENE pygmy stegodonts have been described from the Indonesian islands of Sulawesi, Flores and Timor^1–4 which are now separated by deep seas. Hooijer⁴ suggested that the two forms Stegodon trigonocephalus florensis and Stegodon timorensis apparently coexisted in Flores as well as in Timor, although they may not have been strictly contemporaneous. He concluded that the dwarfing Stegodon populations wandered back and forth between Flores and Timor during the Pleistocene, because otherwise it is hard to see how the two evolutionary products on Timor and Flores could have been so similar. Flores is now separated from Timor by a 3,000 m deep Savu Sea 150 km wide which narrows to 30 km in the Ombai Strait between Alor and Timor (Fig. 1). Because an elephant (and presumably a stegodont) could not swim across the Savu Sea and Ombai Strait, the existence of a land connexion between Flores and Timor during the Pleistocene must be postulated (Fig. 1).