Ordovician Fezouata Shale fossil site at Jbel Tizagzaouine

The Fezouata Biota represents the only major Konservat-Lagerstätte that reflects an open marine Ordovician fauna, and critically documents the earliest stages of the Great Ordovician Biodiversification. It bridges a major gap in our understanding of marine ecosystems between the middle Cambrian and the Silurian (Van Roy et al., 2010; Van Roy et al., 2015b). Among the 185+ taxa identified, some belong to typical post-Cambrian groups (e.g. asterozoans, bivalves, cephalopods, crinoids), while others are icons of exceptionally preserved Cambrian Burgess Shale-type biotas (e.g. lobopodians, radiodonts, sachitids), providing pivotal insight into the origin and evolution of major animal clades (Destombes, 1962; Van Roy et al., 2015b). Furthermore, several Fezouata species (e.g. cheloniellids, phyllodocids, various chelicerates) represent the oldest occurrences of their groups. The sedimentology, stratigraphy, paleoenvironment and geological history of the Fezouata Shale have been characterized in detail, and analyses of Fezouata sediments have significantly refined our understanding of soft-tissue taphonomy (Saleh et al., 2021). Jbel Tigzazaouine represents one of the most complete and easily accessible sections through the main interval of exceptional preservation in the Fezouata Shale, and is the site of some of the most important discoveries. Its sedimentology is typical for the intermediate bathymetry at which the Fezouata Biota lived, and the hill offers an excellent vantage point, overlooking all major geological features of the area.