Oligocene mammals from Ethiopia and faunal exchange between Afro-Arabia and Eurasia

摘要: Afro-Arabian mammalian communities underwent a marked transition near the Oligocene/Miocene boundary at approximately 24 million years (Myr) ago. Although it is well documented that endemic paenungulate taxa were replaced by migrants from Northern Hemisphere, timing and evolutionary dynamics of this have long been mystery because faunas about 32 to Myr ago are largely unknown. Here we report late Oligocene fossil assemblage Ethiopia, which constrains migration postdate 27 ago, yields new insight into indigenous faunal preceded event. The fauna composed large herbivores reveals not only earlier persisted epoch but also demonstrates one group, Proboscidea, diversification. When Eurasian immigrants entered Afro-Arabia, pattern winners losers among endemics emerged: less diverse such as arsinoitheres became extinct, moderately species-rich groups hyracoids continued Miocene with reduced diversity, whereas proboscideans successfully carried their adaptive radiation out Afro-Arabia across world.