Article: The Dinantian Taphrognathus transatlanticus conodont Range Zone of Great Britain and Atlantic Canada

The Taphrognathus transatlanticus Range Zone is proposed to replace the earlier defined, and subsequently rejected, Taphrognathus varians-Cavusgnathus-Apatognathus Assemblage Zone. It is based on the occurrence and range of the conodont species Taphrognathus transatlanticus sp. nov. in strata of Visean age on both sides of the Atlantic Ocean. The T. transatlanticus conodont Range Zone is present in the upper part of the S2 Zone of the Avon Gorge in Great Britain and the lower B Subzone of the Windsor and Codroy groups of Atlantic Canada. The B Subzone has previously been correlated with the S2 (Sub)zone using megafaunal and microfloral criteria; the strati-graphically restricted occurrence of T. transatlanticus sp. nov. supports these correlations. The B Subzone has previously been correlated with the middle late Visean using foraminifera and algal microflora but we suggest that it is middle Visean in age. Our suggestion is supported by previous megafaunal correlations. The upper S2 Zone and the lower B Subzone have both been correlated with the Holkerian Stage of the British Dinantian. The fauna of the T. transatlanticus conodont Range Zone has not yet been found at the boundary stratotype section of the Holkerian at Barker Scar, Cumbria.