Regularities in the Late Cretaceous flora evolution in northwestern Kamchatka and Koryak Highland

Processes responsible for the alternation of flora evolution stages are ana lyzed on the basis of the Late Cretaceous floras from northeastern Russia, among them two paleofloral successions from the Penzhina Bay (Turonian-Camp anian) and the Rarytkin Range (middle Maastrichtian-Danian). Changes in the species diversity and ecosystem structures, as well as the extent of extin ction and origin of taxons, mainly depend on the mode, trend, and sharpness of climatic changes at the stage boundaries and on the flora taxonomic com position. The flora renewal at each stage is significant (40-75% at the spe cies level) and controlled by the intense evolution of flowering plants. Ho wever, there are many transient genera and species of conifers, which often become dominant or subdominant elements among various Late Cretaceous flor as. Climatic conditions, especially humudification, affect the extent of ge ographic differentiation of floras as well.