The Winton Formation flora (Albian–Cenomanian, Eromanga Basin): implications for vascular plant diversification and decline in the Australian Cretaceous

Abstract

The youngest Australian equisetaleans and bennettitaleans are identified within the latest Albian to early Cenomanian Winton Formation flora based on new impression fossils from the Winton district, Eromanga Basin, western Queensland. Typical Winton Formation floras are also confirmed near Isisford and Morney Plains in eastern and central Eromanga Basin. The Winton Formation flora contains over 50 macrofossil plant taxa and marks the transition from seed-fern/conifer to angiosperm dominance in the Australian floristic succession. The pattern of clade representation in Australian late Mesozoic fossil assemblages suggests a causal link between angiosperm diversification and the decline of key understorey and mid-storey plants, particularly equisetaleans, seed-ferns, ginkgophytes and some fern families, through the mid-Cretaceous.

Key words:

• Cretaceous
• leaves
• Equisetales
• Bennettitales
• conifers
• angiosperms
• diversity
• extinction
• Queensland

Acknowledgements

Kristen Spring, Scott Hocknull and Alex Cook facilitated access to materials at the Queensland Museum, and John Laurie helped access specimens housed at Geoscience Australia. Kristina Frantzen NRM, Stockholm, helpfully assisted in coating fossils with ammonium chloride. We thank Liz Kennedy, Mike Pole and Ben Kear for helpful comments on the manuscript. Stephen McLoughlin acknowledges support from the Swedish Research Council (Vetenskapsrådet). Christian Pott is funded by a Swedish Natural History Museum Postdoctoral Fellowship.