Plant communities and climate change in southeastern Australia during the early Paleogene

In this study, data from fossil macrofloras and microfloras in southeastern Australia are used to reconstruct vegetation and climates for the early Paleogene. Our data show that for much of the late Paleocene to middle Eocene, complex, species-rich forests were predominant in southeastern Australia, under mesothermal humid climates (mean annual temperature 16-22 °C, coldest quarter mean temperature >10 °C, mean annual precipitation >150 cm/yr). A minor cooling episode may have occurred in the mid-early Eocene. Megathermal climates may have been present in lowlands in the latest early Eocene, during the Cenozoic Global Climatic Optimum. These forests were dominated by taxa characteristic of present-day mesothermal-megathermal high-rainfall multistratal forests; e.g., Cunoniaceae, Elaeocarpaceae, Gymnostoma (Casuarinaceae), Lauraceae (e.g., Beilschmiedia, Cryptocarya and Endiandra), and Proteaceae. A prominent treefern element (Cyathea and Dicksonia types) was present in the early Eocene. A number of megathermal taxa, including Cupanieae (Sapindaceae) and Ilex (Aquifoliaceae), were present through the early and middle Eocene. Taxa characteristic of modern-day microthermal to mesothermal forests were also present, e.g., Nothofagus (Nothofagaceae), Eucryphia (Eucryphiaceae), Libocedrus (Cupressaceae) and Podocarpaceae (Acmopyle and Dacrycarpus). The relictual araucarian conifer, Wollemia, and other Araucariaceae were present through the late Paleocene to early Eocene. There is limited physiognomic evidence to suggest the late Paleocene to early Eocene forests contained some deciduous canopy trees