The arrival of brachiopods of the Nicolella Community to the Mediterranean margin of Gondwana during the Late Ordovician: Palaeogeographical and palaeoecological implications

• Palaeogeography of the Upper Ordovician Mediterranean localities has been analysed.
• A new and detailed late Katian palaeogeographic reconstruction is proposed.
• Nicolella Fauna migrated from temperate to high latitudes during the late Katian.
• Eastward and poleward water currents of the temperate zone favoured the migration.
• Nicolella Fauna displaced Mediterranean endemic brachiopods in the associations.

The study of brachiopods of the Nicolella Community from the main Upper Ordovician localities of the Mediterranean margin of Gondwana has allowed an accurate analysis of their palaeogeographical relationship. Among the studied localities, the Armorican Massif was located at higher latitudes during the Late Ordovician, followed northward by the Portuguese Central Iberian Zone and the Cantabrian Zone, then by the Iberian Chains. The Pyrenees were located farther north, followed by the Spanish Central Iberian Zone. The northernmost localities were the Montagne Noire, Sardinia and the Carnic Alps. The brachiopod association from the Spanish Central Iberian Zone originated from storm accumulations, resulting in a mixed association composed of a few specimens of taxa characteristic of the Nicolella Community, together with abundant specimens of taxa typical of communities thriving in shallower environments. The anomalous results obtained for this locality in the multivariate analyses can be explained. Brachiopods of the Nicolella Community expanded its distribution during the mid to late Katian from Avalonia and Baltica to the high-latitude carbonate platforms of the Mediterranean margin of Gondwana, presumably taking advantage of the eastward and poleward warm-water currents of the temperate zone. Once settled there, this immigrant fauna occupied new niches created during the Boda event, displacing the endemic Mediterranean faunas to occupy a more marginal role in the associations and eventually driving them to extinction.

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