ABSTRACT: Nine samples of broad Late Cretaceous age, previously studied by the respected Russian diatomistA.P. Jousé, were reexamined in order to document the taxonomic composition of silicoflagellates at several localities within the Ural Federal District of Russia. New observations are provided on the range of morphological variability in several important taxa, and a new morphological term, “segment”, is presented for the basal skeletal components of Cornua. An attempt is also made to refine the age determinations for these samples using a recently established silicoflagellate biostratigraphic zonation for theCanadianmargin.Our general conclusion is that the zonation developed based on the Canadian sections can be successfully used to provide age control for sections exposed in the northern part of Eurasia. The samples studied here are probably correlative to the lower Campanian Cornua trifurcata Partial Range Zone and the lowermost Campanian Schulzyocha ruppelii Range Zone of northern Canada. However, the recognition of the Schulzyocha ruppelii Zone is based on the presence of a secondary zonalmarker (Gleserocha tapiae), due to the absence of Schulzyocha. Thismay indicate that only the Cornua trifurcata Zone has interregional applicability, while the Schulzyocha ruppelii Zone may be restricted to the Canadian successions due to the endemism of Schulzyocha. Further studies on Late Cretaceous silicoflagellate paleobiogeography are required to resolve these issues.
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