EARLY DEVONIAN OSTEOSTRACANS FROM SEVERNAYA-ZEMLYA, RUSSIA

Four new osteostracan species are described from the basal part of the Lower Devonian Spokoinaya Formation on October Revolution Island, Sev ernaya Zemlya Archipelago, Russia: Tauraspis vara, gen. et sp. nov., H apilaspis apheles, gen.. et sp. nov., Severaspis rostralis, gen. et sp . nov. and Benneviaspis urvantsevi, sp. nov. All are referred to the o rder Benneviaspidida, with some reservation in the case of T. rara. S. rostralis is regarded as the sister-group of the Boreaspididae, hithe rto recorded only from the Wood Bay Formation of Spitsbergen. B. urvan tsevi is similar to some of the species of Benneviaspis from the basal part of the Wood Bay Formation of Spitsbergen. The latter two species suggest a correlation between the base of the Spokoinaya Formation an d that of the Wood Bay Formation or the top of the Red Bay Group (Ben Nevis Formation) of Spitsbergen; the osteostracan assemblage would be early Pragian in age. In addition, an undetermined cornuate osteostrac an from the base of the Severnaya Zemlya Formation is similar to some of the large species of Pattenaspis of the Red Bay Group of Spitsberge n. The presence of the closest relative of the Boreaspididae in Severn aya Zemlya strongly suggests dose biogeographic relationships between this area and Spitsbergen during Early Devonian times.