A Fossil Flora From Rafted Plio-Pleistocene Mudstones at Regatta Point, Tasmania.

Abstract

A Late Pliocene-Early Pleistocene flora from Regatta Point on Macquarie Harbour contains pollen, cladodes, flowers and infructescences of Casuarina (s.l.), suggesting that the site of deposition was surrounded by the source plants. However, leaves and shoots of Nothofagus cunninghamii, Eucryphia, Atherosperma moschatum, Quintinia, Acacia, Lagarostrobos franklinii, Phyllocladus aspleniifolius, Podocarpus, Athrotaxis selaginoides and A. cf. cupressoides also occur, along with pollen and spores of the common rainforest species, and it can be inferred that a cool temperate rainforest was present upstream of the site of deposition. This fossil flora represents the earliest evidence to date of modern rainforest elements in Tasmania. Pollen of a number of modern sclerophyll species, including Epacridaceae, Proteaceae and Eucalyptus, is also present.

The presence of a Quintinia leaf in the Regatta Point flora is evidence that some species have become extinct in Tasmania relatively recently. Extant Tasmanian rainforests evolved from more diverse Mid Tertiary rainforests, probably in response to the Late Tertiary cooling and repeated Quaternary glaciations. The same environmental vicissitudes may have also been responsible for the successful establishment of eucalypts on the west coast of Tasmania by the Late Pliocene-Early Pleistocene, resulting in a vegetation probably similar to that now present around Macquarie Harbour.