Wabanbara ringtailensis—a new chelid turtle (Pleurodira: Chelidae) from mid-Miocene deposits of the Riversleigh World Heritage Area in Australia

The mid-Miocene Ringtail Site of the Riversleigh World Heritage Area in Waanyi country, northwestern Queensland, Australia is a particularly productive locality for chelid turtle fossils. Recently, an almost complete chelid skull was recovered from Ringtail Site. This skull is large and shows a combination of features not found in Australian short-necked chelids: an elongate basisphenoid; large orbits; narrow triturating surface; prominent lateral and posterior emarginations; posteriorly tilted cavum tympani; posteriorly extended squamosal; shallow palate; and a long, broad and ventrally flattened trochlear process. The Ringtail Site skull also differs from Australian long-necked chelids in lacking contact between the quadrate and basisphenoid, possessing unfused frontals, a moderately high temporal arch, and a flattened skull. Aspects of skull morphology suggest that the Ringtail Site chelid was an aquatic omnivore that actively searched for food in open water, and may have employed gape-suction feeding. We designate the Ringtail Site chelid as a new genus and species, and phylogenetically distinct from all modern Australian chelid genera as an early diverging member of the radiation. The Ringtail Site chelid could be closely related to the Australian Miocene taxon Birlimarr gaffneyi—the only other extinct Australian chelid species described from relatively complete skull material. Arthur White [[e-mail]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW, Australia, 2052; Anna Gillespie* [[e-mail]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW, Australia, 2052; Suzanne Hand [[e-mail]], Earth and Sustainability Science Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW, Australia, 2052.