THE LAST FRASNIAN ATRYPIDA (BRACHIOPODA) IN SOUTHERN BELGIUM

The last representatives of the order Atrypida on the southern flank o f the Dinant Synclinorium (Vaulx-Nismes area) in Belgium belong to Cos tatrypa, Spinatrypa, Spinatrypina (?Spinatrypina), Spinatrypina (Exatr ypa), lowatrypa, ?Waiotrypa, Desquamatia (Desquamatia) and Desquamatia (?Seratrypa). Among the thirteen described taxa, five are new: Spinat rypa tumuli sp. n., Iowatrypa circuitionis sp. n., ?Waiotrypa pluvia s p. n., Desquamatia (Desquamatia) quieta sp. n. and Desquamatia (?Serat rypa) derelicta sp. n. Supposed lissatrypid 'Glassia drevermanni' Mail lieux, 1936 from the late Frasnian Matagne shales is assigned to the R hynchonellida. On the southern flank of the Dinant Synclinorium and in the Philippeville Massif, the Atrypida become extinct in the Palmatol epis rhenana Zone, significantly below the Frasnian-Famennian (F-F) bo undary. Their extinction coincides with the first appearance of the gr een and black shales of the late Frasnian Matagne Formation, recording a transgressive-hypoxic event. Based on conodont data, this event tak es place earlier on the southern flank of the Dinant Synclinorium than in the Philippeville Massif.