Abstracts of the 1991 conference on vertebrate palaeontology, evolution and systematics, Alice Springs, NT, March 28-30

Interpretation of plant fossils traditionally splits into twocamps; those concerned with 'microfossils' (e.g.pollen and spores) and those concerned with 'macrofossils' (or 'megafossils', e.g.wood, leaves, reproductive structures).It is also traditionally accepted that whereas microfossils provide the general picture of past vegetation, macrofossils generally provide higher taxonomic resolution but represent vegetation from a very restricted area.This dichotomy is currently breaking down in Australia as it is realised that Tertiary vegetation was very complex and the old views of a Tertiary land.scapecovered for most of the time with widespread and uniform rainforest are fast disappearing.In Australia it is clear that macro-and microfossil data, or a combination of the two, can be used for many purposes; e.g.1. Reconstruction of vegetation.At present this is probably best illustrated by the complex Early Tertiary rainforests of Tasmania.2. Determination of primary and secondary factors in plant evolution.For example, the sclerophyll elements in Australian rainforests almost certainly evolved primarily in response to low soil nutrients, with low water availibility being a secondary problem.3. Determination of evolution in response to climate change.Two key Australian plant families, the Fagaceae and Podocarpaceae, provide excellent evidence of long term evolution in response to declining temperature and changing rainfall patterns.4. Leaf form (physiognomy) provides independent evidence of vegetation type and climate. 5.The presence of certain taxa provide evidence of absolute climatic limits.For example, Nothofagus leaves in the Antarctic Pliocene place limits on the minimum prevailing temperatures because of their known temperature requirements for survival (during winter) and their growth and reproduction (during summer).Palaeobotanical research is on the verge of providing a new interpretation of the evolution of the Australian vegetation -the complexity of the emerging data suggests a Tertiary history of diversity, adaptability and regionalism every bit as complex as that which occurs today

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