Terrestrial faunas and habitats of Aldabra during the late Pleistocene

Abstract

Far from being fixed and unchanging, the islands and land areas of the western Indian Ocean are in a dynamic state; the most important variable, apart from tectonic activity, has been the rise and fall of sea level as a consequence of late Pleistocene glacial advances and retreats. Geological studies at Aldabra show that there have been great variations in the land area of the atoll, the topography, and the height above sea level. Moreover, the land has been completely submerged on at least two occasions. Fossil tortoises, crocodiles, lizards, birds and snails illustrate, if fragmentarily, the pattern of colonization and extinction on the Atoll. Although the earliest terrestrial deposits represent vegetated sandy cay habitats colonized by crocodiles, iguanas, petrels, tortoises and snails, the later deposits indicate dissected rocky substrates with meagre soil formation and scrub vegetation more similar to present day Aldabra. However, both the lizard and snail faunas indicate that considerable faunal change has occurred.