LAUSR

Systematics A description of the upper Cenomanian rudist fauna from the western Saharan Atlas, Guir basin and Tinrhert Hamada (Saharan platform) in southern Algeria is presented here. The present study is documented from seven measured stratigraphic sections. The rudist-bearing limestones show different types of diagenetic alteration (e.g., silicification, dissolution and dolomitisation). The rudist fauna consists of canaliculate rudists (Caprinula boissyi, C. sharpei), radiolitids (Sauvagesia sharpei, S. nicaisei, Durania blayaci, D. arnaudi) and requieniids (Apricardia sp.) indicating a late Cenomanian age. The rudist-bearing limestones document in term of biotic zonation and the local environment change an ecologic succession of three rudist biofacies: (B1) caprinulid biofacies, (B2) radiolitid biofacies and (B3) Apricardia biofacies. These are compared to the Cenomanian rudist-bearing successions from around the Mediterranean Tethys, whereas are emphasized and the palaeobiogeographic similarities with the western Mediterranean province are emphasized.