Ideas on the global characteristics of the Vendian System and its fossil abundance have changed fundamentally in recent years. This is especially true of the microphytologic characteristics of the Lower Vendian, which includes a representative association developed worldwide of large acanthomorphic acritarchs of the so-called Pertatataka type. Similar associations of both organic-walled and silicified microfossils are encountered in Lower Vendian rocks of Australia, China, India, and Spitsbergen (see for review and bibliography) and recently have been found on the East European Platform as well. The unique taxonomic composition of Pertatataka-type associations turns them into a reliable tool for correlating Lower Vendian rocks and allows us to solve a series of debatable problems of the Upper Proterozoic stratigraphy. We show in this work how new finds of organic-walled acritarchs from the Ura Formation (Dal'nyaya Taiga Group, Patom Supergroup) make it possible to solve the inveterate strati-graphic problem of the age of these rocks and the status of the Baikalian unit.
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