A review of two paleoecologically different but contemporaneous early Miocene mammal faunas, Merkur-North and Tuchorice, of northern Bohemia is given. Statistics of faunal assemblages and updated faunal lists of the sites are presented. Outlines of paleobotanical record are evaluated in relation to the different environmental conditions. Some typical finds of mammalian forms are briefly introduced. Comparison of the two faunas and floras stress the complex problems of paleoecology