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Abstract: The Cenomanian-Turonian sequence is well exposed in western central Sinai and contains a considerable number of rudist species. The identified rudists belong to Radiolitidae, Hippuritidae and Requieniidae. Fifteen species are described, belonging to ten genera: Requienia, Toucasia, Apricardia, Radiolites, Eoradiolites, Praeradiolites, Sphaerulites, Sauvagesia, Hippurites, and Vaccinites. Eleven species are reported in the Cenomanian and four species in the Turonian. Within the Cenomanian, two new species are described: Requienia tortuosi and Eoradiolites lenisexternus. The genus Requienia and the species Apricardia carentonenis d’Orbigny, Eoradiolites syriacus (Conrad), Sphaerulites agariciformis Delamétherie, Sphaerulites depressus Blanckenhorn and Vaccinites cf. grossouvrei (Douvillé) are reported for the first time from Egypt. The Cenomanian and Turonian rudists in the western Sinai show either elevator or clinger morphotypes, with the predominance of the former type; recumbent mode of life is rarely represented by some Requieniidae. The elevators are of isolated and clustered occurrences and more represented in the Cenomanian sequence. Rudists of the study area are mainly of parautochthonous fabrics with low to dense packing. Autochthonous fabrics are also achieved by some species, mainly in the Turonian. The disappearance of rudists from the middle part of the sequence and above the Cenomanian/Turonian boundary is due to a deeper setting that resulted from sea-level rise or seafloor subsidence (shelf drowning). The occurrence of rudists with oysters and other benthic fossils in the siliciclastic and carbonate sediments of the Cenomanian and Turonian sedimentary rocks in the Sinai indicate that the sequence was deposited on a broad, shallow shelf. Although the first marine transgression invaded the central Sinai in the late Cenomanian, transgressive deepening conditions continued until the Turonian. The rudists of central Sinai are of Tethyan affinity with significant relation with North Africa, the Middle East, and Southern Europe. [Copyright &y& Elsevier]

The present study deals with the Cenomanian–early Turonian ostracods in the southern Sinai, Egypt. The investigated sequence includes the Raha and Abu Qada formations. The Raha Formation consists of distinctive Cenomanian taxa such as Cytherella aegyptiensis , Veeniacythereis maghrebensis , V. jezzineensis , V. streblolophata streblolophata , Monoceratina trituberculata , and Glenocythere reticulata. Based on the ostracod species, four local biozones are recognized, including Veeniacythereis jezzineensis – Metacythereopteron berbericum , Cytherella eosulcata – Xestoleberis derorimensis , Amphicytherura ziregensis and Perissocytheridea istriana – Cythereis fahrioni. The paleobiogeography of the considered ostracods suggests that there are two bioprovinces, the first of which is the North African province and includes Egypt, Tunisia and Algeria. The second bioprovince represents the Middle East province and includes Lebanon, Oman and Iran. The strong resemblance between the two bioprovince indicates a relatively good communication along the margin of Southern Tethys during the Cenomanian and improved marine ostracod exchange. [ABSTRACT FROM AUTHOR]

Le Crétacé supérieur de la partie orientale des Monts des Ksour (Atlas saharien, Algérie) est classiquement subdivisé en trois formations lithostratigraphiques fossilifères : El Rhelida (Cénomanien inférieur), Mdaouer (Cénomanien inférieur-moyen) et Rhoundjaïa (Cénomanien supérieur-Turonien inférieur). La partie occidentale des Monts des Ksour, moins documentée et peu étudiée à ce jour, fait l'objet ici d'une étude sédimentologique et paléontologique détaillée. À Hassi Djeifa (région de Forthassa), le Crétacé supérieur est représenté par la partie supérieure de la Formation de Mdaouer puis par la Formation de Rhoundjaïa. Les dépôts attribués à la Formation de Mdaouer sont constitués de marnes rougeâtres ou verdâtres, intercalées de calcaires bio-laminés, de calcaires bioclastiques à gastéropodes et bivalves et de grès. Les niveaux marneux ont livré une faune composée d'ostracodes (Damonella spp., Ilyocypris ? sp., Cypridea sp. et Paracypria ? sp.), de sélaciens (Mafdetia tibniensis et Baharipristis bastetiae) et de pycnodontiformes. Les deux espèces de sélaciens (Ordre des Rajiformes) n'étaient jusqu'ici connues que du Cénomanien inférieur d'Egypte. Les données sédimentologiques et paléontologiques suggèrent un âge cénomanien inférieur probable pour les dépôts étudiés et indiquent un paléo-environnement de plaine côtière continuellement influencée par l'action de marées. The upper Cretaceous of the eastern part of the Ksour Mountains (Western Saharan Atlas, Algeria) is classically subdivided into three fossiliferous lithostratigraphic formations: El Rhelida (lower Cenomanian), Mdaouer (lower-middle Cenomanian) and Rhoundjaïa (upper Cenomanian-lower Turonian). The western part of the Ksour Mountains, which is less documented and poorly known, is here the subject of a detailed sedimentological and palaeontological study. Near Hassi Djeifa locality (Forthassa) the upper Cretaceous is represented by the upper part of Mdaouer Formation and by the lowermost part of Rhoundjaïa Formation. The deposits attributed to the Mdaouer Formation are composed of reddish or green marlstone intercalated by biolaminated limestone, bioclastic limestone with gastropods and bivalves, and sandstone. The selachians (Mafdetia tibniensis , Baharipristis bastetiae), pycnodontiform fishes, and ostracod fauna (Damonella spp., Ilyocypris ? sp., Cypridea sp., Paracypria ? sp.) coming from marly beds are studied in detail. The two selachian species (Order of Rajiformes) were so far restricted to the Early Cenomanian of Egypt. Our sedimentological and palaeontological data support a probable Early Cenomanian age of the studied deposits and indicate a coastal plain palaeoenvironment continually influenced by the action of tide. [ABSTRACT FROM AUTHOR]