Some middle and late Cambrian trilobites and brachiopods from the Adamsfield Trough, Tasmania

Abstract

Jago, J.B., Bentley, C.J., Laurie, J.R. & Corbett, K.B., 26 June 2018. Some middle and late Cambrian trilobites and brachiopods from the Adamsfield Trough, Tasmania. Alcheringa 43, 1-17. ISSN 0311-5518.

Cambrian Series 3 and Furongian trilobites and brachiopods are described from the Adamsfield Trough in southwestern Tasmania. The oldest fossils are very poorly preserved trilobites, assigned to Asaphiscidae gen. et sp. indet. from within the Island Road Formation a short distance above the unconformity with the underlying Proterozoic Wedge River Beds. A trilobite species from within the isolated Boyd River Formation is referred to Lioparia sp. The Island Road Formation and the Boyd River Formation are stratigraphically equivalent to the Trial Ridge Beds which have previously been dated as belonging to the Lejopyge laevigata Zone. The Trial Ridge Beds are overlain unconformably by the Singing Creek Formation. In the Adamsfield, Clear Hill and Stepped Hills areas, stratigraphic equivalents of the Singing Creek Formation collectively contain the trilobites Pseudaphelaspis sp., Pseudaphelaspis? sp., Prochuangia sp., Mindycrusta sp., Nepeidae gen. et sp. indet., and Olenidae gen. et sp. indet. plus the brachiopods described herein as Billingsella sp. aff. costata, Billingsella sp. A, Billingsella sp. B and a possible member of the Billingselloidea. The Singing Creek Formation has been previously correlated with the Stigmatoa diloma Zone. The genus Lotosoides Shergold 1975 is placed in synonymy with Prochuangia Kobayashi 1935.

James B. Jago* [[email protected]] University of South Australia, School of Natural and Built Environment, Mawson Lakes, SA 5095, Australia; Christopher J. Bentley [[email protected]] 30 Albert Street, Clare, SA 5453, Australia; John R. Laurie [[email protected]] Department of Biological Sciences, Macquarie University, NSW 2109, Australia; Keith D. Corbett [[email protected]] 35 Pillinger Drive, Fern Tree, Tas 7054, Australia.

Key words:

• Adamsfield Trough
• Tasmania
• trilobites
• brachiopods
• Cambrian Series 3
• Furongian

Acknowledgements

Many of the fossils from the equivalent of the Singing Creek Formation were collected by geologists of the Geological Survey of Tasmania during the mapping of the Huntley and Pedder 1:50 000 sheets. These included P.W. Baillie, A.V. Brown, C. Calver, K.D. Corbett, N.J. Turner and M.J. Clarke. The fossils from along the Gordon River Road were collected by J.B. Jago and K.D. Corbett. The assistance of the present and former curators, Sue Cameron, Penny Williamson, Kathi Stait, Fernando Della Pasqua and Isabella von Lichtan of the Department of Earth Sciences, University of Tasmania, is gratefully acknowledged. Tim Topper is thanked for a constructive review.