Lower Devonian (Pragian–Emsian) land plants from Alexandra: an early window into the diversity of Victorian flora from southeastern Australia

Abstract

Numerous fragmentary plant fossils are described from the Lower Devonian outcrops near Alexandra, Victoria, southeastern Australia. These outcrops include Eglinton Cutting and two road cuttings on Mount Pleasant and Halls Flat roads previously examined by Isabel Cookson in 1935. Most plants are preserved as iron-stained impressions or coalified compressions lacking internal anatomy in fine-grained sandstone and siltstone. The vast majority of specimens examined proved to be little more than naked fragmentary axes often distributed seemingly randomly; it is the exceptions to these that are examined herein. Most of these specimens belong to the zosterophylls and isolated axes with emergences suggestive of a Gosslingiaceae affinity. Significantly, one specimen attributable to Cooksonia Lang, 1937, renalioid-like sporangia and specimens with isolated sporangia with emergences are recorded for the first time from Victoria. A discussion follows examining the possible reasons for the differences between the Alexandra and Walhalla assemblages, and it is postulated that the differing palaeocurrents indicate the terrestrial sources were from opposite directions. This easterly source for the Walhalla assemblage suggests a subaerial environment may have existed on the eastern side of the Melbourne Zone during the deposition of the Norton Gully Sandstone, earlier than the fluvial deposits of the Middle Devonian Cathedral Beds. Fearghus R. McSweeney FGS [ tidal75@gmail.com ], School of Science, RMIT University, Swanston Street, Melbourne 3000, Australia; Jeff Shimeta [ jeff.shimeta@rmit.edu.au ], School of Science, RMIT University, Swanston Street, Melbourne 3000, Australia; John St. J. S. Buckeridge FGS [ john.buckeridge@rmit.edu.au ], Earth & Oceanic Systems Group, RMIT University, GPO Box 2476.