ARCHAEORADIOLITES, A NEW GENUS FROM THE UPPER APTIAN OF THE MEDITERRANEAN REGION AND THE ORIGIN OF THE RUDIST FAMILY RADIOLITIDAE

摘要: Archaeoradiolites gen. nov. (Radiolitidae), mainly characterized by radially arranged branching walls structuring the outer shell layer, includes two species, Archaeoradiolites primitivus et sp. and Archaeoradiolites hispanicus (type species), the distinction of which is based on size, habit development of the radially microstructure. Their geographical distribution is restricted to south-east Spain south-west France, i.e. Western European Tethyan margin, whereas data from Black Sea coast Turkey suggest a possible extension Eastern margin. Each species has distinct biostratigraphic distribution within the Upper Aptian (mainly Gargasian). Agriopleura is suggested be direct ancestor Archaeoradiolites, which in turn considered as progenitor Eoradiolites. The onset Radiolitidae associated with global oceanic changes that favoured calcite opposed aragonite biomineralization. The acquisition porous shell microstructure appears, many respects, biologically advantageous may account for gaining rapid (< 1 myr) ecological ability efficient colonization and occupation space family earlier phase its radiation.