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.