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Abundant and diverse microfossils from shales of the uppermost Ura Formation, central Siberia, document early to middle Ediacaran life along the southeastern margin of the Siberian Platform. The Ura Formation is well exposed in a series of sections in the Lena River basin but the best microfossil assemblages come from a locality along the Ura River. Here, the uppermost twenty meters of the formation contain diverse microfossils exceptionally well preserved as organic compressions. Fossils include nearly two dozen morphospecies of large acanthomorphic microfossils attributable to the Ediacaran Complex Acanthomorph Palynoflora (ECAP), a distinctive assemblage known elsewhere only from lower, but not lowermost, to middle Ediacaran rocks. Discovery of ECAP in strata previously considered Mesoproterozoic through Cryogenian confirms inferences from chemostratigraphy, dramatically changing stratigraphic interpretation of sedimentary successions and Proterozoic tectonics on the Siberian Platform. Systematic paleontology is reported for 36 taxa (five described informally) assigned to 23 genera of both eukaryotic and prokaryotic microfossils. One new genus and two new species are proposed: Ancorosphaeridiurn magnum n. gen. n. sp. and A. minor n. gen. n. sp. [ABSTRACT FROM AUTHOR]

Discusses integrated chronostratigraphy of the Proterozoic/Cambrian boundary beds in the western Anabar region in northern Siberia. Parasequences identified in the sequence corresponding to the Manykai Formation; Correlation of the Staraya Reckha Formation with sub-Tommotian carbonates in southeastern Siberia.

Presents data taken from sedimentary rocks in the western Anabar region, northwestern Siberia. Sub-Tommotian unconformity in southeastern SIberia; Anabar lithostratigraphy and biostratigraphy; Chemostratigraphic correlation; Stratigraphic and evolutionary implications.

Presents a discussion on the paper `Sizing up the sub-Tommotian unconformity in Siberia,' by Andrew H. Knowl et al. Stratigraphic magnitude of the unconformity at the base of the Pestrotsvet Formation in the stratotype area of the Tommotian Stage; Assemblages of small shelly fossils.