A new Bothriembryon from the Nullarbor Plain, Western Australia, with insights on the age of Bothriembryon praecursor from Kangaroo Well, Northern Territory

Abstract

Fossil Bothriembryon specimens were recovered from the northwestern edges of the Nullarbor Plain, Western Australia, ∼300 km inland from the current southern coastline. This locality is significant because extant species of Bothriembryon from the Nullarbor are confined to within 50 km of the coastline. Principle component analysis (PCA) was used to compare the Nullarbor Bothriembryon species with a morphologically comparable extant species from the Eucla Basin, Bothriembryon barretti, and geographically closest fossil species: Bothriembryon kremnobates and Bothriembryon praecursor. Results showed strong support for a new fossil species herein described as Bothriembryon pilkiensis sp. nov. Specimens were found as internal moulds within pisolitic calcrete overlying the early Miocene Colville Sandstone. The chronology of the pisolitic calcrete is poorly studied; here we discuss the results of palynological and U–Th disequilibrium investigations which attempted to constrain the time of deposition and fossilization, with palynology results suggesting the late Pliocene. The type locality of B. praecursor, Kangaroo Well, Northern Territory, was also re-evaluated in age to the early Miocene, using biocorrelation of two balbarid species to taxa found within Riversleigh World Heritage Area assemblages. http://zoobank.org/urn:lsid:zoobank.org:pub:E33B1587-1023-419D-AFE8-11FD8C443A27

Helen E. Ryan [[email protected]], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106; Kenny J. Travouillon [[email protected]], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106; Lynne A. Milne [[email protected]], School of Earth and Planetary Sciences, Curtin University, Kent Street, Bentley, WA, 6102; Sarah K. Martin [[email protected]], Geological Survey of Western Australia, Department of Energy, Mines, Industry Regulation and Safety, 100 Plain Street, East Perth, WA, 6004; Kailah M. Thorn [[email protected]], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106; Corey S. Whisson [[email protected]], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106.

Keywords:

• Stylommatophora
• Pliocene
• palynology
• pisolites
• Ulta Limestone
• Etadunna Formation
• biocorrelation

Acknowledgements

We thank the Spinifex People, including Ethan Hansen and the Spinifex Rangers, for enabling us to conduct fieldwork on Country and consultation throughout the project. We also thank Pila Nguru (Aboriginal Corporation) for facilitating access to the area and consultations with Traditional Owners. Natalie Schroeder (Geoscience Australia), Liliana Stoian (GSSA) and Adam Yates (NTM) for loan of specimens, and Alison Miller (AM) provided images and measurements of type specimens. Jian-Xin Zhao and the University of Queensland Radiogenic Isotope Facility conducted and interpreted the U–Th analysis. Mikael Siversson (WAM), Nic Campione and Marissa Betts (University of New England), Kate Trinajstic (Curtin University) and Bram Breure (Naturalis Biodiversity Centre) contributed insightful discussions, advice, and support. Kirsten Tullis (WAM) for technical assistance. Comments from the anonymous reviewers improved our manuscript. SKM publishes with permission from the Executive Director of the Geological Survey of Western Australia.

Disclosure statement

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

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03115518.2024.2323472.

Additional information

Funding

This work was supported by the Minderoo Foundation and the Geological Society of Australia WA Division Student Bursary fund.