Palaeocene Middle Eocene Dinocysts

Circum-Antarctic early Palaeogene dinocyst associations were recovered from the Tasmanian Gateway (between Australia and East Antarctica, e.g. Brinkhuis et al., 2003), New Zealand (e.g. Wilson, 1978, 1984, 1988; Willumsen, 2000; Crouch, 2001) and Seymour Island (e.g. Askin, 1988a,b; Elliot et al., 1994). The associations are characterized by nearly identical composition and stratigraphic succession. While circum-Antarctic endemic taxa were present at least since the Maastrichtian (e.g. Riding and Crame, 2002; Brinkhuis et al., 2003), the taxa often referred as the ''Transantarctic Flora'' established itself in the early Palaeogene in an otherwise largely cosmopolitan assemblage. Since the late Early Eocene, the influence of the ''Transantarctic Flora'' (constituted by species such as Deflandrea antarctica, Octodinium askiniae, Enneadocysta partridgei, Vozzhennikovia spp., Spinidi-nium macmurdoense and Arachnodinium antarcticum) increases until the middle Late Eocene.

While the younger part of the circum-Antarctic Middle Eocene is comparatively less well studied, with records only from New Zealand (e.g. Wilson, 1988; Strong et al., 1995), DSDP Sites 280 and 281 (Crouch and Hollis, 1996), Seymour Island (Wrenn and Hart, 1988), the Scotia Sea (Mao and Mohr, 1995), ODP Site 1172 (Brinkhuis et al., 2003) and southern Argentinean successions (e.g. Guerstein et al., 2002), a broad similarity is apparent. The younger part of the Southern Ocean Middle Eocene appears to be characterized by several important last occurrences (LOs), including those of Membranophoridium perforatum, Hystrichosphaeridium truswelliae, Hystrichokolpoma spinosum and Hystrichokolpoma truncatum (cf. Wilson, 1988; see Brinkhuis et al., 2003).

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