The trilobites Prophalaron gen. nov. (Calymenidae) and Dicranurus (Odontopleuridae) from the Upper Ordovician of New South Wales

Abstract

Previously undescribed trilobites from the Late Ordovician (latest Eastonian, mid Katian) Gunningbland Formation of central New South Wales include the calymenid Prophalaron jonesi gen. et sp. nov. and the odontopleurid Dicranurus webbyi sp. nov. Prophalaron resembles some members of the Reedocalymeninae, in particular Neseuretinus, in the presence of a relatively long, convex preglabellar field and a short, upturned anterior border. However, this similarity is a result of convergence, and other characters such as the weaker vaulting of the cephalon and pygidium as well as the hypostomal morphology indicate that Prophalaron belongs to the Calymeninae. Dicranurus webbyi is the first odontopleurid recorded from the Ordovician of Australia. The species lacks the reduction in length of the fifth thoracic segment and its posterior pleural spine that have been suggested as diagnostic of the genus.David J. Holloway [dhollow@museum.vic.gov.au], Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia; Patrick M. Smith* [Patrick.Smith@austmus.gov.au], Australian Museum, 1 William Street, Sydney, New South Wales 2010, Australia; Geoff Thomas [fossilgt@gmail.com], PO Box 130, Southland Centre, Victoria 3192, Australia. *Also affiliated with: Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.