The First Discovery of Colonial Radiolarians in Jurassic Sediments (Arctic Zone of Siberia)

A representative of the colonial radiolarians of the genus Siphonosphaera has been discovered in the Upper Jurassic (lower substage of the Volgian Stage = Lower Tithonian) deposits of the Bazhenovo Regional Substage on the Yamal Peninsula in the Arctic periphery of Western Siberia. This discovery is important for understanding the geological history of colonial radiolarians. A new species, Siphonosphaera yamalica Vishnevskaya et Amon, sp. nov. is described.