Ostracods of the Cenomanian-Turonian transition in the Ksour and Amour Mountains (Saharan Atlas, Algeria): systematic and palaeobiogeographic implications

Abstract

The study of ostracods from the Cenomanian-Turonian transition in the Ksour and Amour Mountains (Saharan Atlas, Algeria) has allowed the identification of fossil assemblages characterising this relevant time interval characterised by global environmental changes. The ostracod assemblages consist of fifteen species and seven genera, and are dominated by the Family Cytherellidae (mainly genus Cytherella), and secondarily by the families Paracyprididae (exclusively Paracypris) and Trachyleberididae (mainly Cythereis). Less common are components of families Bairdiidae, Bythocypridae and Macrocyprididae. The studied ostracod assemblages were compared with those assemblages from basins belonging to palaeobiogeographic provinces of North Africa-Middle East (Gondwana Palaeomargin) to search for possible similarities among basins. Thus, the results obtained show the proximity of the ostracod fauna of the Moroccan and Egyptian basins, to which the two basins belonging to the Middle East (Jordan and Oman) are related, the strong similarity between the basins of the Saharan Atlas (Algeria and Tunisia) and finally, the isolation of the ostracod fauna of the Lebanese Basin. This palaeobiogeographical topology shows the probable existence of communication routes during the Cenomanian-Turonian transition or equivalent palaeoenvironmental conditions in different basins.