A Synthesis of the Rich Gondwana Triassic Megafossil Flora from Nymboida, Australia

This synthesis of the Nymboida megafossil flora, based on a series of nine descriptive taxonomic papers, provides the first comprehensive account of a Triassic fossil flora in Australia in the twenty-first century. From a fossil flora perspective the Nymboida Coal Measures, located southwest of the city of Grafton in northern New South Wales, are highly significant as they are the source of the oldest commercial coal seams in the world following the "coal gap" after the disastrous Permian-Triassic extinction events. Similarity of the Nymboida flora to the Kaihikuan floras of New Zealand suggests a Ladinian age. The previously active Coal Mine and Reserve Quarries, which lie in the Basin Creek Formation, have yielded over many years a very rich and diverse Triassic flora. To date a total of 58 genera, 105 species and another 28 forms that have insufficient detail preserved for specific identification have been described. Due to a tectonic heating event during the Cretaceous, cuticles are not preserved. The flora is particularly diverse in ferns (14 species) and fern-like fronds (23 species), whereas bryophytes and sphenophytes are rare. The Ginkgoopsida, which includes the so called seed-ferns and ginkgo-like leaves, are rare (e.g., Rochipteris) to being among the dominant elements (e.g., Dicroidium, Sphenobaiera, Lepidopteris, Ginkgoites and Kurztiana) of the flora. Cycadophyta are very rare to rare with one species of Pseudoctenis being common. The Voltzialean conifer Heidiphyllum may occur in monotypic assemblages, as a codominant with the other common conifer Rissikia or with other common species. Among the leaves of uncertain classification are Taeniopteris, with one common species, and other genera – Nilssonia, Linguifolium, Gontriglossa and Scoresbya – being rare to very rare.