Macrofossil Casuarinaceae: Their identification and the oldest macrofossil record, Gymnostoma antiquum sp nov, from the Late Paleocene of New South Wales, Australia

The oldest known Casuarinaceae macrofossils, from late Paleocene sediments at Lake Bungarby in New South Wales, are assigned to a new species of Casuarinaceae, Gymnostoma antiquum. The nearest living relatives of this species are the Papua New Guinean Gymnostoma species and in particular one as yet unnamed species. Previous problems relating to the preparation, identification and description of Casuarinaceae macrofossils are examined and clarified. The ecology of both living Gymnostoma and G. antiquum are discussed. The decrease in catastrophic disturbance and climate seasonality during the Cenozoic were probably major contributing factors leading to the current distribution of Gymnostoma.