Article: A new Early Devonian galeaspid from Bac Thai Province, Vietnam

A new large galeaspid, Bannhuanaspis vukhuci gen. et sp. nov., is described from the top part of the Si Ka Formation or the base of the Bac Bun Formation (Early Devonian, Late Lochkovian or Early Pragian) in the Phu Luong District, Bac Thai Province, northern Vietnam. The overall shape of its head shield is suggestive of the 'Polybranchiaspidiformes', but this morphology is regarded as a primitive feature for the Galeaspida. Its transversely elongated median dorsal opening, broad posterior margin of head shield am posterolaterally directed main lateral-line are also regarded as primitive galeaspid characteristics. However, it shares with the ' Polybranchiaspidiformes' and Huananaspidiformes a large number of gill openings, and with the Galeaspidiformes very short and rounded cornual processes.