Author	Kurita, H. and Matsuoka, K.
Year	1994
Journal	Review of Palaeobotany and Palynology, vol. 84 (1994): pp. 129-153.Review of Palaeobotany and Palyn
Title	Trinovantedinium boreale Bujak-dominated dinoflagellate assemblages in Eocene-Oligocene stratified water in northern Japan.

Abstract Kurita, H. and Matsuoka, K., 1994. Trinovantedinium boreale Bujak-dominated dinoflagellate assemblages in Eocene-Oligocene stratified water in northern Japan. Review of Palaeobotany and Palynology, vol. 84 (1994): pp. 129-153. Abstract Dinoflagellate assemblages in marine late Middle Eocene to Early Oligocene formations in northern Japan are exceptionally limited in diversity and generally dominated by Trinovantedinium boreale. Other species in the assemblages include Bellatudinium hokkaidoanum Kurita and Matsuoka, sp. nov., Paralecaniella indentata, and Selenopemphix spp. The "restricted flora" developed particularly in Hokkaido, where earlier studies indicated a paleoenvironment of relatively shallow embayment with saline, stratified water. The persistent restriction in species composition was presumably influenced by the stratification and relatively low water temperature. The assemblages were also possibly influenced by high phytoplankton productivity which enhanced the dominance of peridiniacean forms. B. hokkaidoanum Kurita and Matsuoka, sp. nov. and the wide morphological variation of T. boreale are described.