Early Devonian osteostracans from Severnaya Zemlya, Russia

Four new osteostracan species are described from the basal part ofthe Lower Devonian Spokoinaya Formation on October Revolution Island, Severnaya Zemlya Archipelago, Russia: Tauraspis rara, gen. et sp. nov., Hapilaspis apheles, gen. et sp. nov., Severaspis rostralis. gen. et sp. nov. and Benneviaspis urvantsevi, sp. nov. All are referred to the order Benneviaspidida, with some reservation in the case of T. rara. S. rostralis is regarded as the sister-group of the Boreaspididae, hitherto recorded only from the Wood Bay Formation of Spitsbergen. B. urvantsevi is similar to some of the species ofBenneviaspis from the basal part ofthe Wood Bay Formation of Spitsbergen. The latter two species suggest a correlation between the base of the Spokoinaya Formation and that ofthe Wood Bay Formation or the top of the Red Bay Group (Ben Nevis Formation) of Spitsbergen; the osteostracan assemblage would be earl y Pragian in age. In addition, an undetermined cornuate osteostracan from the base of the Severnaya Zemlya Formation is similar to some of the large species of Pattenaspis of the Red Bay Group of Spitsbergen. The presence ofthe closest relative ofthe Boreaspididae in Severnaya Zemlya strongly suggests close biogeographic relationships between this area and Spitsbergen during Early Devonian times.