| Despite the considerable differences in faunas from three widely separated areas in the Early Cretaceous world (Argentina, the Mediterranean area and NW Europe) eight genera are common to all three: Valanginites, Olcostephanus, Karakaschiceras, Neohoploceras, Neocomites, Oosterella, Spitidiscus, and Crioceratites. Across two well-marked intervals (mid Valanginian and mid Hauterivian) the faunas are sufficiently close to allow correlation across the whole area. These represent intervals of global sealevel rise. |
