Author	Mao Shaozhi and Mohr, B.A.R.
Year	1995
Journal	Review of Palaeobotany and Palynology 86 (1995): 235-263
Title	Middle Eocene dinocysts from Bruce Bank (Scotia Sea, Antarctica) and their paleoenvironments and paleogeographic implications

Abstract Mao Shaozhi and Mohr, B.A.R., 1995; Middle Eocene dinocysts from Bruce Bank (Scotia Sea, Antarctica) and their paleoenvironments and paleogeographic implications. Review of Palaeobotany and Palynology 86 (1995): 235-263 An early Middle Eocene (calcareous nannofossil Zone CP 13b) dinocyst flora from a piston core from Bruce Bank, South Scotia Ridge (Antarctica), comprises 70 species and subspecies belonging to 34 genera. This unusual diversity for these high southern latitudes is interpreted to be a reflection of the Eocene climatic optimum. One new species, Phthanoperidinium antarcticum Mao and Mohr, sp. nov., is described. High ratios of terrestrial vs. marine kerogen and distribution of the dominant dinocyst species indicate nearshore deposition. The lower part of the section is dominated by peridinoid cyst species of Deflandrea and Phthanoperidinium, while in the upper part, gonyaulacoid cysts, mainly Areosphaeridium diktyoplokus, are the major constituents. This change suggests increasing water depths (from about 800 to 1500 m) in a nearshore to offshore setting. The cyst flora contains 37 species endemic to southern high latitudes and can be assigned to the "transantarctic biogeographic province"; 27 of the cyst taxa are known from temperate areas while 13 thick walled taxa are considered typical for cool to cold water environments. Using modern data sets for comparison, we estimate winter surface water paleotemperatures at about 5 to 10¦C, summer temperatures might have reached more than 14¦C.