Abstract Detail

Paleobotany

Rozefelds, Andrew [1], Dettmann, Mary [1], Clifford, Trevor [1].

Cenozoic macrofloras of northern Australia - new floras, new taxa and new approaches.

The Cenozoic fossil floras of northern Australia remain poorly known. Although the earliest descriptions were undertaken by Constantin von Ettingshausen in the late 19^th century, there has been little subsequent research undertaken. An overview of the Cenozoic floras of northern Australia, i.e. above 28^oS, is presented.
Three principal floral assemblages will be discussed: The oldest floras (Paleogene) are from Dinmore; Australia being still joined to Antarctica. Only the ferns in the Dinmore site have been studied in any detail. Three taxa are recognized, the climbing fern Lygodium (Schizaeaceae), aquatic fern Tecaropteris (Pteridaceae) and a third undescribed taxon. Spores extracted from sporangia of the same Lygodium species, collected from southern Australian sites, have been referred to Cyathidites splendens Harris 1965. The Dinmore site also includes a diverse angiosperm flora.
Younger Oligo-Miocene floras are associated with small sedimentary basins related to hot spot volcanic activity. Australia was at this time separated from Antarctica, becoming the “island” continent. The most studied flora, from Capella, is Late Oligocene/early Miocene in age and includes 3D preserved (silicified) seeds and fruits. The Capella flora consists of trees - Elaeocarpus spp. (Elaeocarpaceae), Wilkinsonia (Proteaceae), Spondylostrobus and Pleiogynium (Anacardiaceae), Fontainocarpa (Euphorbiaceae), conifers, lianas (Vitaceae, two species) and Menispermaceae, and ferns. Using a nearest relative approach, the flora is interpreted as a complex mesophyll/notophyll rainforest with lianas.
New floras have been found recently. Miocene impression floras from the Mount Warning Shield Volcano provide credible evidence of Eucalyptus and rainforest taxa including Nothofagus, Lauraceae, Myrtaceae, Proteaceae and legumes in the same site. The flora is associated with Miocene volcanics dated using ⁴⁰K/³⁹Ar to between 23–26 m.y. B.P. A flora from Moranbah, Central Queensland has yielded a new species of Lygodium with spores referable to Crassiretitriletes vanraadshovenii Germeraad, Hopping & Muller 1968, Gymnostoma staminate and pistillate cones and foliage (Casuarinacaeae), Nothofagus leaves, other flowering plants and conifers. Miocene sites in kaolinite from the Kingaroy area in southern Queensland have also additional evidence of Gymnostoma.
Amber from Cape York Peninsula, of uncertain age, has yielded Acacia-like flowers, fungi and bryophytes.
An overview of the taxa recorded from northern Australia is provided highlighting some recent discoveries. These studies collectively provide additional information on the origins and history of the modern Australian flora. Computer tomography and synchrotron imaging is providing new insights into the silicified fruits from the Capella flora.

1 - Queensland Museum , Geosciences , 122 Gerler Road , Hendra, Brisbane , Queensland, 4011, Australia

Keywords:
Cenozoic
Paleogene
Miocene
northern Australia
Synchrotron
Macrofloras.

Presentation Type: Oral Paper
Session: 28, Mesozoic to Pleistocene Paleobotany
Location: 102/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 3:45 PM
Number: 28009
Abstract ID:264
Candidate for Awards:None