Lower Devonian (Lochkovian) thelodonts from October Revolution Island (Severnaya Zemlya Archipelago, Russia)

Two new thelodont species, Turinia composita n. sp. and Nikolivia aligera n. sp., and two already known, Boreania minima Karatajute-Talimaa, 1985 and Canonia sp. cf. C. grossi Vieth, 1980, are described. Isolated scales of all of them are distributed at different levels of the Pod''emnaya Formation outcropping along the Matusevich, Pod"emnaya and Spokojnaya rivers. Thelodont assemblage from the lower part of the Formation allows a correlation with the Lochkovian series of Laurussia, e.g., with the lower Lochkovian part of Canadian Arctic.