Conodonts in the Silurian of Severnaya Zemlya and Sedov archipelagos (Russia), with special reference to the genus Ozarkodina Branson & Mehl, 1933

The studied conodont faunas indicate that the main part of the Silurian sequence on Severnaya Zemlya and Sedov archipelagos (Vodopad, Golomyannyj, Srednij formations and the lower part of the Samojlovich Formation) is of Llandovery age. Llandovery ozarkodinids are dominated by Ozarkodina waugoolaensis Bischoff, 1986; Oz. aldridgei Uyeno & Barnes,1983 occurs at some levels; Oz. guiyangensis Zhou, Zhai & Xian, 1981 and Ozarkodina sp. E characterize the Golomyannyj Formation. From the Wenlock strata only Oz. confluens bucerus (Viira, 1983) has been found. Oz. polinclinata Nicoll & Rexroad, 1968 is very rare, and Oz. excavata (Branson & Mehl, 1933) is evidently missing in this region. Several poorly represented new species of Ozarkodina Branson & Mehl, 1933 are kept in open nomenclature.