The taxonomy and palaeobiogeography of small chorate dinoflagellate cysts from the Late Cretaceous to Quaternary of Antarctica

Abstract

Small chorate dinoflagellate cysts are common in Upper Cretaceous to Quaternary sedimentary successions around the Antarctic margin. Taxonomic confusion surrounding dinoflagellate cysts and acritarchs of similar morphology throughout the southern high palaeolatitudes has hitherto limited investigation of their palaeoecological significance. This study aims to solve the taxonomic problems, and to allow a new assessment of dinoflagellate cyst acmes. A detailed morphological study of new material from the López de Bertodano Formation of Seymour Island, Antarctic Peninsula, is presented. These dinoflagellate cysts are identified as Impletosphaeridium clavus Wrenn & Hart 1988 emend. nov. Their gross morphology and their vast abundances in the James Ross Basin are strongly suggestive of dinoflagellate blooms. This scenario implies similarities to modern dinoflagellate cysts from the polar regions.

Keywords:

• dinoflagellate cysts
• acritarchs
• taxonomy
• palaeobiogeography
• Cretaceous-Quaternary
• Antarctica

Acknowledgements

This research was funded by a Natural Environment Research Council (NERC) Antarctic Funding Initiative (AFI) project (Grant NE/C506399/1) entitled ‘Terminal Cretaceous climate change and biotic response in Antarctica’ and a subsequent related NERC project entitled ‘Impact of global disturbances on the evolution of life in the polar regions during the Cenozoic’ (Grant NE/100582X/1). The fieldwork was supported logistically by the British Antarctic Survey. Vanessa C. Bowman thanks the TransAntarctic Association and the Antarctic Science Bursary for additional financial support and Eric Condliffe (formerly of the Leeds Electron Microscopy and Spectroscopy Centre, University of Leeds) for technical assistance. James B. Riding publishes with the approval of the Executive Director, British Geological Survey (NERC). The authors wish to thank Rex Harland, Kenneth N. Mertens, Meriel Fitzpatrick and Sophie Warny for constructive reviews that significantly improved the manuscript.