Faunal turnovers of Palaeogene mammals from the Mongolian plateau

Most orders and many families of modern mammals were established during the Palaeogene. Mammalian evolution during this period of time has been correlated with global climatic events(1-4) although the timing mode and scale of such a climate-evolution link remain debatable(1,5,6). The Palaeogene global climate was step-punctuated by a warming across the Palaeocene/Eocene boundary about 55 Myr ago and a cool-off throughout the late Eocene and early Oligocene epochs(1,2,7-10). The most severe cooling was at 33.5 Myr, slightly after the Eocene/Oligocene boundary, and was characterized by a drop in the mean annual temperature and by changes in vegetation from Eocene dense forests to Oligocene more open country(5). Here we analyse 33 Palaeogene mammal faunas from the Mongolian Plateau of China and Mongolia. There is a distinct pattern of faunal turnovers: perissodactyl-dominant faunas of the Eocene were abruptly replaced by rodent/lagomorph-dominant faunas of the Oligocene. We interpret the turnovers as having been effected by global climatic shifts and name the prominent biotic reorganization across the Eocene/Oligocene boundary the Mongolian Remodelling; which correlates to the European Grande Coupure.