The Late Cretaceous flora of the Khatanga depression

Fossil plants from the Late Cretaceous deposits of the Khatanga depression are joined in three floristic assemblages: the Ledyanaya assemblage (the Turonian-Coniacian), the Kheta assemblage (the late Coniacian-early Santonian) and Mutino assemblage (the late Santonian-early Campanian). The Ledyanaya floristic assemblage contains ferns (Anemia rarinervis Abramova), cycadophytes (Nilssonia sp.), ginkgoales (Ginkgo ex gr. sibirica Heer), conifers (Taxodium sp., Sequoia tenuifolia (Schmalh.) Sveshn. et Budants.) and angiosperms (Pseudoprotophyllum hatangaense Abramova, Liriodendropsis simplex (Newb.) Newb., Trochodendroides sp., ะกissites sp., Dicotylophyllum sp.). The characteristic features of this assemblage are depauperated composition of angiosperms and survival of the Early Cretaceous relic elements. The Kheta floristic assemblage contains only Taxodium sp. and Trochodendroides sp. The Mutino floristic assemblage contains Sequoia tenuifolia, Pseudoprotophyllum hatangaense, Quereuxia angulata (Newb.) Krysht. ex Baik. and Cobbania corrugata (Lesq.) Stockey, Rothwell et Johnson. The Ledyanaya floristic assemblage is very similar with the Newsiberian flora from the Derevyannye Gory Formation of New Siberia Island. The Mutino floristic assemblage have common elements with Kundur flora (the Campanian) from the Kundur Formation of Amur region. The abundance of large leaves of Pseudoprotophyllum in the Mutino flora is evidence of the preservation of humid warm-temperate climate in the northern part of Siberia up to the Campanian. The presence of water plants Quereuxia angulata and Cobbania corrugada indicates the westward migration of some characteristic elements of the Pacific ocean lowlands.