Abstract The early Late Ordovician (Sandbian 1) representatives of the Tafilalt Biota in the locality of Bou Nemrou (Jbel Tjarfaïouine) provide examples of fossil preservation in medium-grained sandstones with abundant microbially induced sedimentary structures. The recorded trilobite assemblage comprises 11 species of ten genera, among which one is new (Placoparia africana Pereira & Gutiérrez-Marco, sp. nov.) and four others previously regarded as endemic to the locality are considered to be synonymys of species already described from Bohemia. The oldest representative of the illaenid genus Cekovia is recorded, revised diagnosis proposed for the genus Mytocephala Struve and for Uralichas tardus Vela & Corbacho. Parvilichas Corbacho & Vela is considered to be a junior synonym of Uralichas Delgado. From a palaeobiogeographical point of view, the Bou Nemrou locality shows strong relationships with trilobite assemblages from the Dobrotivian and with the lower Berounian sandstone facies of Bohemia, reinforcing the correlation of both regions. Some soft-bodied structures are recognized here, including the digestive tracts of Uralichas and the traces of paired, metameric axial bands in the anterior thoracic segments of the trilobite Selenopeltis preserved in apatite and interpreted as intersegmental musculature.

Abstract The Ordovician successions of France and neighbouring areas of Belgium and Germany are reviewed and correlated based on international chronostratigraphic and regional biostratigraphic charts. The same three megasequences related to the rift, drift and docking of Avalonia with Baltica can be tracked in Belgium and neighbouring areas (Brabant Massif and Ardenne inliers), western (Rhenish Massif) and northeastern Germany (Rügen). The remaining investigated areas were part of Gondwana in the Ordovician. The Armorican Massif shares with the Iberian Peninsula a Furongian–Early Ordovician gap (Toledanian or Norman gap), and a continuous Mid–Late Ordovician shelf sedimentation. The Occitan Domain (Montagne Noire and Mouthoumet massifs), eastern Pyrenees and northwestern Corsica share with southwestern Sardinia continuous shelf sedimentation in the Early Ordovician, and a Mid Ordovician ‘Sardic gap’. In the Ordovician, the Maures Massif probably belonged to the same Sardo-Occitan domain. The Vosges and Schwarzwald massifs display comparable, poorly preserved Ordovician successions, suggesting affinities with the Teplá-Barrandian and/or Moldanubian zones of Central Europe.