COMPOSITION AND AGE OF THE GREBENKA FLORA FROM THE ANADYR' RIVER AREA (THE MIDDLE CRETACEOUS, NORTHEASTERN RUSSIA)

Abstract

The Grebenka flora comprising over 120 species of horsetails, ferns, gymnosperms, and angiosperms was found in a number of exposures of the upper subformation of the Krivaya Rechka Formation, the middle course of the Anadyr' River. Palynological and paleomagnetic data on the flora-bearing beds, their relationships with overlying marine deposits, and taxonomic compositions of different Krivaya Rechka plant assemblages suggest the late Albian-early Turonian age of the Grebenka flora and the late Albian-early Cenomanian age of the classic Eliseev flora. Two different overwintering strategies could be favorable for the Grebenka plants: the shedding of foliage and the evergreen state. In the latter case, the plants developed xeromorphic features protecting them from an excessive moisture loss during the dark winter and reducing the plant resources necessary for the metabolism.