Palynological-age determination of Early Cretaceous vertebrate-bearing beds along the south Victorian coast of Australia, with implications for the spore-pollen biostratigraphy of the region

Abstract

Palynology is used to provide new age controls for the coastal exposures yielding Early Cretaceous vertebrate faunas in the Otway and Gippsland basins, southeast Australia. This work shows all vertebrate-bearing deposits in the Otway Basin are Albian in age. On the eastern margin of Cape Otway, vertebrate-bearing deposits are attributed to the early Albian Crybelosporites striatus Zone, except for one in the younger Coptospora paradoxa Zone. To the west of Cape Otway, the sampled deposits range from the oldest zone in the Albian, the C. striatus Zone, to the C. paradoxa and Phimopollenites pannosus zones, providing a complete section of the Albian stage. In the Gippsland Basin, the structural setting of vertebrate deposits is more complicated and large portions of the coastal exposures consist of repeated sections controlled by small-scale faults. Sites in this region lie below or above the Barremian/Aptian boundary. However, owing to the paucity of age indicator species, some sampled deposits remain undated. In this basin, the ranges of certain key palynomorph species (e.g., Pilosisporites notensis and Pilosisporites parvispinosus) differed from those outlined in some previously published biostratigraphic schemes. The discovery of the angiosperm pollen Clavatipollenites hughesii in the lowermost Aptian deposits of the Gippsland Basin is consistent with its first occurrence elsewhere in Australia and shows it is a reliable indicator for the Aptian stage. This study shows that there is currently a collection bias towards vertebrate assemblages that are latest Barremian and early Albian in age.

Barbara E. Wagstaff [[email protected]], The School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; Stephen J. Gallagher [[email protected]], The School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; W. Michael Hall [[email protected]], School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia; Vera A. Korasidis [[email protected]], Smithsonian Institution, National Museum of Natural History, Department of Paleobiology, NHB121, 10th and Constitution Avenue, NW, Washington, DC20013-7012, USA; Thomas H. Rich [[email protected]], Melbourne Museum, 11 Nicholson Street, Carlton, Victoria 3053, Australia; Doris E. Seegets-Villiers [[email protected]], School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia; Patricia A. Vickers-Rich [[email protected]], School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, Australia and Swinburne University of Technology, Department of Chemistry and Biotechnology, Faculty of Science, Hawthorn, Victoria 3122, Australia.

Keywords:

• Early Cretaceous
• palynology
• Otway Basin
• Gippsland Basin
• vertebrate fossils

Acknowledgements

We would like to thank Geoscience Australia and the Melbourne Museum for the loan of some of the slides. We would also like to thank Global Geolab Limited for altering their standard processing techniques. Robert Hills collected pollen samples from Devils Kitchen, Ross Brown some samples from Dinosaur Cove, Arnold Dix some samples from Eagles Nest, Mark Nan Tie, Andrew Constantine and Hamed Aghaei collected some samples from the Gippsland sites, Katherine Charlton samples from Black Head and Doris Seegets-Villiers collected a large sample set from the Caves/DDFS/Flat rocks area. We would particularly like to thank Mike Cleeland for his major contribution to the fieldwork. David Cantrill, Pip Cleeland, Gil Hollins, Jane Lindsay, Jennifer McEwen Mason, Martin Norvick, Alan Tait, Anne-Marie Tosolini assisted with some of the fieldwork. We would like to thank Wendy White for producing maps and lists of vertebrate faunas and the sites from which they were recovered. Draga Gelt helped by drafting the maps. We thank Parks Victoria and the local Rangers for several permits and their help that, over the years, have allowed us access to these field areas, to Monash University for both monetary support and coverage of the OH&S oversight and finally to a large number of volunteers who have on many occasions found the sites and helped in the excavations that have led to this biostratigraphic study. We would like to particularly thank the Chief Editor of Alcheringa (Benjamin Kear), Associate Editor (Stephen McLoughlin) and two reviewers for vastly improving the paper. The project was undertaken on the land of the Bunwurrung (Gippsland) and Gadubanud (Otway) peoples and we thank them for their hospitality.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

We would like to acknowledge that this project was partially funded by a Bicentennial Gold 88 Endowment and ARC Linkage, grant LP0989203 with industry partners Lakes Oil N.L., Nexus Energy and Geotrack International Pty. Ltd. All new fieldwork and research was funded by National Geographic Grant number 9644-15, titled ‘Dating the Dinosaurs’.