Enriching the Late Devonian plant record of Australia: A Frasnian assemblage from Gooloogong, New South Wales

Abstract

For Devonian palaeobotany, Australia represents one of the most geologically well-documented areas of the understudied Gondwana palaeocontinent. Despite this asset, the Australian plant record is still insufficiently known for this period. This situation is detrimental to a satisfactory understanding of the evolution and diversification patterns of vascular plants at a crucial moment in Earth's history, when they acquired modern attributes and when the main extant lineages originated. This paper documents a plant assemblage from a locality near the town of Gooloogong in central New South Wales, based on fossils collected in 1973 (A. Ritchie, R. Jones, Australian Museum), and by our team in 2004. Fossils are preserved in the form of casts, adpressions preserving external morphology, and permineralizations showing internal anatomy. The Lycopsida are represented by Leptophloeum rhombicum, the Cladoxylopsida by Denglongia cf. hubeiensis, and the Progymnospermopsida by various organs attributed to the Archaeopteridales, i.e., a root of Callixylon sp., branches of Archaeopteris sp., and a leaf of Archaeopteris macilenta. This association, which is typical of the Frasnian of South China, supports a Frasnian age for the Gooloogong plant assemblage. It also confirms the existence of floristic exchanges between the northeastern part of Gondwana and South China at this time, and supports a trend towards the homogeneization of floras during the Late Devonian.