Devonian conodonts and ammonoids occurring in association in the Ouidane Chebbi section of the
     eastern Tafilalt (Anti-Atlas, Morocco) are described and analysed in terms of stratigraphy.  The excel-
     lently exposed sequence spans the entire Devonian; it includes open-marine carbonates and shales
     deposited outside the tropical realm.  Except for its Middle Devonian part, the Ouidane Chebbi section
     is not condensed.  Although the sequence was only sampled in a preliminary fashion, most of it litho-
     logical units have been dated with some precision.  The study is an attempt to enhance the precision in
     the correlation between the Devonian conodont and ammonoid sequences.  Graphic correlation method
     was used for estimating the precise position of the zonal and stage boundaries for the Middle and Upper
     Devonian intervals.  The stratigraphy of the Lower Devonian at Ouidane Chebbi is still poorly defined.
     The Eifelian/Givetian boundary is well constrained, especially by both conodonts and ammonoids. lt
     occurs within the uppermost part of the Kacák Event-Level, a characteristic shale horizon that begins
     in the ensensis Zone and ranges into the hemiansatus Zone.  Biostratigraphic indications from con-
     odonts show that the top of the Pharciceras limestone unit is located within the norrisi Zone and the
     Givetian/Frasnian boundary should be placed within the characteristic black styliolinites level of the
     Frasne Event.  The onset of the Kellwasser facies falls within the Zone 12 (winchelli Zone) of the
     Frasnian and it extends into the rhomboidea Zone.  The combined evidence from ammonoid and trilo-
     bite data suggests that the marine deposition persisted at Ouidane Chebbi at least up to the time of the
     Upper praesulcata Zone.