New insights on the Lower Ordovician linguliformean brachiopods of the Anglo-Brabant Massif and the Stavelot-Venn Inlier (Belgium)

The Lower Ordovician (Tremadocian) linguliformean brachiopods of the southeastern part of the Anglo-Brabant Massif are documented systematically for the first time. The material belongs to a single Belgian locality (La Roche-en-Brabant), situated in one of the few valleys that incise the Mesozoic-Cenozoic cover, and more precisely from the topmost part of the siliciclastic Mousty Formation (Tangissart Member). Here, minute, poorly diverse linguliformeans are associated with planktic graptolites (Rhabdinopora) and nileid trilobites (Platypeltoides). They consist of three species belonging to three genera (Obolidae and Elkaniidae), of which only Broeggeria is known with certainty, due to the poor preservation of the material. In the Belgian part of the Stavelot-Venn Inlier, the presence of linguliformean brachiopods within the Floian Les Plattes Member of the Ottré Formation, which were reported more than 150 years ago, remains unconfirmed. The genus Broeggeria, known from several Belgian Tremadocian localities, is a relic from the Cambrian brachiopod fauna. By the Tremadocian it is well established globally between the Low-Latitude and High-Latitude provinces. The Belgian assemblage has strong similarities with assemblages from Baltica reflecting the early Palaeozoic changing palaeogeography.