Early Ordovician trilobites from Barnicarndy 1 stratigraphic well of the southern Canning Basin, Western Australia

Abstract

Twenty-three trilobite taxa are described here from the Early Ordovician (Tremadocian to Floian) Nambeet Formation retrieved from the Barnicarndy 1 drillcore, Canning Basin, Western Australia. This includes one new genus, Veeversaspis gen. nov., and six new species: Asaphellus zheni sp. nov., Madiganaspis lauriei sp. nov., Norasaphus (Norasaphus) jagoi sp. nov., Rodingaia leggi sp. nov., Sanbernardaspis excalibur sp. nov., and Veeversaspis jelli gen. et sp. nov. This fauna can be divided into three stratigraphically distinct assemblages, the Apatokephalus sp.–Veeversaspis jelli gen. et sp. nov. Assemblage (2177.50–2382.94 m depth), Asaphellus trinodosus Assemblage (2030.07–2177.52 m depth), and Asaphellus zheni sp. nov. Assemblage (1595.83–2001.88 m depth). The two stratigraphically lowest assemblages are consistent with a late to latest Tremadocian age (both within the Paroistodus proteus Zone). The third, and highest, assemblage is consistent with a mid-Floian age (within the Oepikodus communis Zone). This systematic contribution refines previous biostratigraphic work based on an age-diagnostic conodont fauna and demonstrates the stratigraphic utility of using multiple taxonomic groups for more robust biostratigraphic age estimates. P.M. Smith [ Patrick.Smith@austmus.gov.au ], Palaeontology Department, Australian Museum Research Institute, Sydney, New South Wales, 2010, Australia, and Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia. H.J. Allen [ heidi.allen@dmirs.wa.gov.au ], Geological Survey of Western Australia, Department of Mines, Industry Regulation and Safety, Mineral House, 100 Plain Street, East Perth, Western Australia, 6004, Australia.