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 [ helen.ryan@museum.wa.gov.au ], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106; Kenny J. Travouillon [ Kenny.travouillon@museum.wa.gov.au ], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106; Lynne A. Milne [ L.Milne@curtin.edu.au ], School of Earth and Planetary Sciences, Curtin University, Kent Street, Bentley, WA, 6102; Sarah K. Martin [ sarah.martin@dmirs.wa.gov.au ], Geological Survey of Western Australia, Department of Energy, Mines, Industry Regulation and Safety, 100 Plain Street, East Perth, WA, 6004; Kailah M. Thorn [ Kailah.thorn@museum.wa.gov.au ], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106; Corey S. Whisson [ corey.whisson@museum.wa.gov.au ], Collection and Research Centre, WA Museum, 49 Kew Street, Welshpool, WA, 6106.