Fossil elephantoids, Awash paleolake basins, and the Afar triple junction, Ethiopia

The most diverse collection of fossil elephantoids from a single area, are contained in the 1-km-thick hominid-bearing Awash Group. These deposits range from late Miocene to Holocene in age and are found in the Awash Valley of the Afar Depression, Ethiopia. Uniquely, the Afar elephantoids inhabited a series of internal lake basins splayed out across an evolving, subaerial triple junction created by the separation of the African, East African and Arabian plates. The spatial and temporal distribution of elephantoids in these basins demonstrates that these animals were progressively drawn into the central Afar with the divergence of the three plates. As such, the elephantoids moved from the higher margins of the East African and African plates to the depressed lowlands of the triple junction, where subsiding and migrating lake basins served as ideal habitats for large herbivores with high water requirements. This pattern of migration serves as a model for the migration of animals into intercontinental areas and for their dispersal across plate boundaries.