Biogeographical land bridges of Bali-Nusa Penida-Lombok: A possible dispersal pathway for terrestrial fauna during the Pleistocene Glacial periods

Abstract

Fossil records in the Lesser Sunda region provide evidence of colonization by prehistoric humans and terrestrial fauna, dating back to the Pleistocene glacial periods. We believe that Nusa Penida was once part of a dispersal pathway connecting a biogeographical land bridge between Bali and Lombok. Therefore, in this study, we aim to identify the presence of this land bridge using a bathymetric map and reconstruct it at different global sea levels corresponding to glacial conditions. The study also examined the Bouguer Gravity Anomaly to estimate its lithological characteristics. The results indicate that land bridges possibly existed on both the western and eastern sides of Nusa Penida during the Pleistocene glacial periods, at least since 800,000 years ago. These land bridges directly connected the southern part of Bali to the southern part of Lombok. As sea levels rose during interglacial periods, they gradually submerged. Particularly on the eastern side, the remnants of the land bridge are located approximately 225 meters below the modern sea level. This land bridge seemingly experienced intense abrasion due to the pre-modern Indonesian Throughflow (ITF); local tectonic events might also be responsible. This study provides insights into land-based biogeographical dispersal pathways across the Wallace Line.