Chitinozoaires de la formation du Ktaoua inférieur, Ordovicien supérieur de l’Anti-Atlas (Maroc) [Chitinozoa from the Lower Ktaoua Formation, Upper Ordovician of the Anti-Atlas (Morocco)]

The Lower Ktaoua Formation of the Anti-Atlas (Morocco) yields numerous but poorly preserved chitinozoans. Three main assemblages have been recognized. The first one is representative of the Costonian-Lowermost Harnagian. It is restricted to the lowermost part of the Lower Ktaoua Formation. The second assemblage occurs only in the Lower Tiouririne Member and suggests an early Caradocian age. The third one is restricted to the Agadir-Tissinnt Member and corresponds to the Uppermost Caradoc - Early Ashgill. This new datum modifies previous stratigraphical assignments based on macrofossil evidence. The Upper Ordovician chitinozoan assemblages from Morocco display large affinities with European contemporaneous material.