The Yana floristic assemblage from the Upper Cretaceous volcanic deposits of the northern coast of Sea of Okhotsk
The Yana floristic assemblage occurs from tuffs and tuffites of the upper part of the Ola Formation (the Campanian) of the Okhotsk-Chukotka volcanogenic belt (OCVB). The locality is situated in the upper part of the Yana River basin (Magadan Region). The Yana assemblage is composed of 18 taxa: Polypodiophyta: Cladophlebis sp., Mygdykitia ochotica Golovn. et Shczep., gen. et sp. nov. Cycadopsida: Ctenis paljavaensis Philipp. Czekanowskiopsida: Phoenicopsis ex gr. angustifolia Heer Pinopsida: Picea yanensis Golovn. et Shczep., sp. nov., Pkea sp., Pityostrobus sp., Pityolepis sp. 1, 2, Pityocladus sp., Cupressinocladus sp., Elatocladus anorovii Golovn. et Shczep., sp. nov. Magnoliopsida: Quereuxia angulata (Newb.) Krysht. ex Baik., Trochodendroides sp. 1, 2, Dicotylophyllum sp. 1-3. Among them, three species and one genus are firstly described. According to general systematic composition the Yana floristic assemblage is similar to the Ola flora (the Campanian) from the Arman River and the Maltan River basins and has some common taxa with the Chaun flora (the Coniacian) of the Central Chukotka. But the Yana assemblage does not contain typical species of the Ola and the Chaun floras and differs from them by some endemic species. The Yana floristic assemblage comes from coarse-grained weakly stratified tuffites, whereas the plant remains of the Ola flora are usually connected with fine-grained bedded volcanogenic-terrigenous lacustrine deposits. It is possible to assume, that the Yana floristic assemblage reflects the vegetation of upland slope habitats, whereas the Ola flora characterizes the vegetation of lowlands near the lakes at volcanic plateau.