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The marine and terrestrial palynology of the Middle Jurassic Wanaea verrucosa Zone from the Perseus-3A, Sunrise-2 and Sunset West-1 wells in the North West Shelf of Australia has been studied in detail. These three wells represent brackish and shallow marine successions from the Northern Carnarvon and Bonaparte basins respectively. The palynological data derived from these three wells constitute the basis for the formal definition of this important dinoflagellate cyst biozone and its three constituent subzones. The inception of Wanaea verrucosa defines the base of the Wanaea verrucosa Zone, and the base of the oldest subdivision, the Lower Wanaea verrucosa Subzone. Dinoflagellate cyst floras in the Lower Wanaea verrucosa Subzone are relatively sparse and low in diversity; species richness increases up-section. The base of the succeeding Middle Wanaea verrucosa Subzone is defined by the range base of Valvaeodinium spinosum. The youngest subdivision is the Upper Wanaea verrucosa Subzone; it is defined by the incoming of the large and distinctive species Endoscrinium kempiae. Other stratigraphically important datums include the inceptions of cf. Bradleyella adela in the Lower Wanaea verrucosa Subzone, Valveodinium “cookii” and Wanaea lacuna in the Middle Wanaea verrucosa Subzone, and Endoscrinium spp. and Ternia balmei within the Upper Wanaea verrucosa Subzone and the range tops of Mancodinium semitabulatum subsp semitabulatum and Nannoceratopis deflandrei subsp. senex in the Middle Wanaea verrucosa Subzone. An undescribed form, Meiourogonyaulax “straussii”, occurs throughout the Wanaea verrucosa Zone. The age of the Wanaea verrucosa Zone is interpreted as being Late Bajocian to Early Bathonian; the floras are very reminiscent of the Bajocian-Bathonian transition of the Northern Hemisphere. The dinoflagellate cyst associations are dominated by cosmopolitan taxa, particularly at the generic level. Endemic Australasian forms such as Endoscrinium kempiae and Ternia balmei are relatively minor in significance. Taxa with epicystal and multiplate precingular archaeopyles are prominent; this represents the coeval evolutionary explosion of the gonyaulacacean dinoflagellate cysts observed in the latest Early to Late Bajocian of Europe. By contrast, the succeeding Callovian to Oxfordian interval in Australasia and Europe is dominated by endemic taxa. This may be an indication of the development of forms with specific environmental preferences during the Callovian and Oxfordian and/or the establishment of barriers to the passive dispersal of dinoflagellates within Tethys. However this phenomenon may be partially an artefact of further diversification.

Palynology, Jurassic, Australia