The offshore Mesozoic-Tertiary Bight and Duntroon basins formed through rifting and separation of the Australian and Antartic plates. Palynological investigation of samples dredged during BMR Rig Seismic Cruise 66 showed that the bulk of the palynofloras correlate with the Maastrichtian to earliest Paleocene Forcipites (al.Tricolpites longus) spore/pollen Zone and the Manumiella druggii microplankton Zone. These zones are characteristic of the upper Potoroo Formation, thus this part of the formation is widespread in the basins, indicating paralic to marine depositional environments. Of the other samples, one possibly came from the early Tertiary Pidinga Formation, and two from each of the Bight and western Duntroon basins contain Santonian to Maastrichtian palynofloras indicating a lower Potoroo/Wigunda Formation source flowing from the east and north into the Great Australian Bight area. Palynological evidence indicates that lowland temperate rainforests were widespread on the Australian side of the rift at least during the Campanian- Maastrichtian.