Original paper

Ammonoids from the late Givetian Taouzites Bed of Ouidane Chebbi (eastern Tafilalt, SE Morocco)

Bockwinkel, Jürgen; Becker, Ralph Thomas; Aboussalam, Zhor Sarah

Abstract

A marly, nodular limestone bed at Ouidane Chebbi in the eastern Tafilalt (eastern ramp of the Tafilalt Platform, SE Morocco) yielded a rich and diverse ammonoid fauna of the late Givetian Taouzites taouzensis Zone (MD III-D), which falls in the higher part of the Polygnathus dengleri sagitta Subzone of the conodont succession. There are seventeen species of twelve ammonoid genera, which include several new taxa: Pharciceras elevatum n. sp., Ph. concurrens n. sp., Oxypharciceras chebbiense n. gen. n. sp., Extropharciceras worki n. sp., Allopharciceras maximum n. gen. n. sp., and A. kirchgasseri n. gen. n. sp. The most common forms are Pseudoprobeloceras pernai, Taouzites taouzensis, and Synpharciceras clavilobum. The comparison with contemporaneous faunas of the adjacent Tafilalt and Maider basins shows a different faunal composition, characterized by the new genera and species, as well as by the rarity/absence of Lunupharciceras and otherwise common species of Pharciceras and Extropharciceras. This difference probably reflects the different bottom water oxygenation and meso- versus eutrophic conditions, rather than just water depth. Apart from three species, our Ouidane Chebbi fauna is also very different from that of the underlying Syn. clavilobum Zone (MD III-C) of the central Tafilalt Platform. This significant extinction coincides with a marked regional regression.

Keywords

conodontssystematicsgivetianmoroccodevonianpalaeoecologytaxonomyammonoids