Paléobiodiversité et paléoenvironnements: l'exemple des gisements de poissons téléostéens du Messinien préévaporitique d'Oran et du bassin du Chélif (Algérie)

Re-examination of Arambourg’s collection of Messinian fossil fishes from Oran and the Chelif Basin, Western Algeria and the study of Dr Léopold Geslin’s material collected at Oran-Ravin Blanc (Gambetta-Saint-Eugène) old quarry has allowed an improvement of the paleoecological interpretation of the fish faunas from this region. The importance of upwellings was demonstrated in this locality because myctophids, which have a mesopelagic way of life, are by far the dominant components (62%). At Sig, their influence was less important, although myctophids are still relatively abundant (29%). In contrast, the fish fauna from Oran-Raz-el-Aïn is indicative of a shallow water nearshore environment in which neritic, littoral and pelagic fishes where living together, whereas the occurrence of rather scarce myctophids suggests that a deep sea was present in the vicinity. The study of the fish fauna from Sidi Brahim is based on an abundant material in which more taxa were identified. However, a detailed geological field work would be useful for a better understanding of its paleoecological significance. The same remarks can be applied to the locality called Renault (Sidi M’hamed Ben Ali) which was not sufficiently sampled.