THE AMMONITES FROM THE EARLY AND MIDDLE L IAS FROM THE CENTRAL HIGH ATLAS OF BENI-MELLAL - TAXONOMY AND ACUTE BIOSTRATIGRAPHY

Eighteen biostratigraphical horizons are founded on the analysis of th e Sinemurian and Pliensbachian succession in the High-Atlas of Beni-Me llal area. That sequence which implies more than 45 ammonites species is the first one performed with the horizon precision for the lower an d middle Lias of the whole North Africa. It could be used as foundatio n of a future biochronological framework suitable for the considered p eriods and for the Maghreb or even for the whole Tethyan Mediterranean areas. Correlations with the N-W European standard zonation and with the southern Spain biochronological framework are easy and reliable fo r the Middle - Upper Carixian and for the Domerian but are difficult a nd tentative for the older levels. At last, two Early Carixian new spe cies, Miltoceras taguendoufi and Metaderoceras apertum, are described.