AN EARLY TERTIARY MACROFLORA FROM WEST DALE, SOUTHWESTERN AUSTRALIA

The Middle Eocene - Oligocene macroflora from West Dale in southwestern Australia is described. The majority of fossils are leaves, and 35 taxa are described and illustrated, including 12 new fossil species and three previously described species (two fossil, one extant). There are clear floristic similarities with Eocene - Oligocene macrofloras in eastern Australia (e.g. Agathis, Dacrycarpus, Gymnostoma, Cunoniaceae, Nothofagus, Lauraceae, Banksieaephyllum), but the West Dale flora is unique in the predominance of Myrtaceae and, to a leaser extent, Proteaceae. The West Dale macroflora offers support for the hypothesis that the Australian sclerophyll flora evolved primarily in response to low nutrient levels (especially phosphorus) and was pre-adapted to developing xeric climates. However, alternative hypotheses cannot be ruled out.