Early Aptian (Early Cretaceous) freshwater bivalves from the Australian–Antarctic rift, southeast Victoria

Abstract

Australian Mesozoic freshwater and estuarine bivalves belonging to the Hyriidae, Glauconomidae and Sphaeriidae have been described from only a few localities in Queensland, New South Wales and South Australia, revealing a low-diversity fauna. The hyriids Megalovirgus flemingi McMichael, 1956, and Megalovirgus stirlingi sp. nov. are among the first Cretaceous freshwater bivalves to be described from Victoria and were recovered from upper Strezlecki Group (lower Aptian) strata, ca 4 km southwest of Inverloch, Gippsland Basin. These strata represent major fluvial flood deposits that accumulated in the Australia–Antarctica rift during the Early Cretaceous breakup of eastern Gondwana. The distribution of Megalovirgus flemingi in the Cretaceous of both New Zealand and Victoria indicates close links in the freshwater faunas between Zealandia and southeastern Australia during the Early Cretaceous.

Key words:

• Gondwana
• Early Cretaceous
• southeastern Australia
• Inverloch
• Gippsland Basin
• upper Strzelecki Group
• freshwater bivalves
• Hyriidae
• Megalovirgus

Acknowledgements

The authors thank Rolf Schmidt (MV) for access to the material, and Mary Walters, Lesley Kool and their team of volunteers who collected the specimens and were helpful at the fossil excavation. Excavations were sponsored by the National Geographic Society, the Australian Research Council and Altlas Copco under research permits issued to Patricia Vickers-Rich, the current being No. 10004616 of Dept. Sustainability and Environment, National Parks, Victoria. We are grateful to Steve Morton for photography, Steve Poropat, Chris Mays and Jozua van Otterloo (Monash University) for helpful insights, and Scott Hocknull (Museum of Queensland) and Pat Vickers-Rich (Monash University), Tom Rich (MV) for providing reference material. We thank Steve McLoughlin, Steven Good, Alan Tait and an anonymous reviewer for constructive feedback. Research was supported by a Monash Research Initiatives grant to JS, and PhD scholarship to DT.