Late Givetian ammonoids from Ait Ou Amar (northern Maider, Anti-Atlas, southeastern Morocco)

摘要

Hypoxic late Givetian shales with a goethitic/haematitic mixed neritic-pelagic fauna from "Butte 760" west of Ait Ou Amar in the northern Maider, eastern Anti-Atlas, southeastern Morocco, yielded a diverse ammonoid assemblage, which consists of 21 species belonging to 13 genera. There are four new species, Mzerrebites amarensis n. sp., Extropharciceras gentile n. sp., Ex. serum n. sp., and Petteroceras angustum n. sp., and several taxa identified in open nomenclature. The loose assemblage mostly falls in the Anti-Atlas Taouzites taouzensis Zone but also includes forms representing the preceding Synpharciceras clavilobum Zone as well as index species of the topmost Givetian Petteroceras errans Zone. The comparison with the rich, roughly contemporaneous assemblage from the deeper Tafilalt Basin (Hassi Nebech) enables to identify taxa that were probably generalists (tornoceratids), or that preferred more shallow (Pseudoprobeloceras praecox) or deeper habitats (e.g., Lunupharciceras, Pluripharciceras plurilobatum, and Synpharciceras). The majority of species common to both localities show no ecomorphological differences.