Late Cenomanian–early Turonian ammonites from the Western Saharan Atlas (Algeria)

Abstract

ABSTRACT New palaeontological and biostratigraphic data from the Cenomanian–Turonian deposits of the western Saharan Atlas are presented in this study. More than 300 specimens of ammonites were collected from Kebeur es Seguia and Aïn El Orak sections, representing the Rhoundjaïa Formation. With the exception of the three ammonites previously described from the western Saharan Atlas by former authors [namely Neolobites vibrayeanus (d’Orbigny), Vascoceras gamai Choffat and Vascoceras cauvini Chudeau], nine additional ammonite species [Calycoceras (Calycoceras) cf. naviculare (Mantell), Eucalycoceras cf. pentagonum (Jukes-Brown), Metoicoceras geslinianum (d’Orbigny), Nigericeras gadeni (Chudeau), Fikaites subtuberculatus (Collignon), Pseudaspidoceras pseudonodosoides (Choffat), Fagesia peroni Pervinquière, Fagesia tevesthensis (Peron) and Choffaticeras (Choffaticeras) sinaiticum (Douvillé)] are described and illustrated from the studied area. Biostratigraphic analysis revealed four ammonite biozones; three from the late Cenomanian namely, the Neolobites vibrayeanus Total Range Zone, the Metoicoceras geslinianum Total Range Zone and the Vascoceras cauvini Total Range Zone; and one from the early Turonian (earliest Turonian), the Choffaticeras sinaiticum Total Range Zone. The recognised ammonite zones demonstrate a significant palaeobiogeographical relationship between the studied area and other countries of North Africa, the Middle East, South America and southern Europe.