Palaeontological Society of Southern Africa 16th Biennial Conference, University of Cape Town 5–8 September 2012 (An index to authors is given on page 58) Basal therocephalian from the Middle Permian 2 Vancouver, British Columbia, Canada. Former postdoctoral fellow in the Zoology of South Africa: taxonomy and geographic and Department, University of Cape Town, Rondebosch, South Africa
[email protected] temporal distribution We present a detailed study on variation of the dental Abdala, Fernando; Day, Michael; Rubidge, Bruce morphology and replacement in the Early Triassic Bernard Price Institute for Palaeontological Research, Palaeosciences Centre, cynodont Thrinaxodon liorhinus. For this study we analysed University of the Witwatersrand, East Campus, Private Bag 3, WITS 2050, Johannesburg, South Africa five specimens ranging from 37–87 mm in skull length
[email protected] using micro computed tomography (microCT) scanning Important changes in amniote taxonomic representation techniques, which were supplemented by detailed ana- occurred during the Middle Permian, the most significant tomical analysis of 41 specimens with a basal skull length being an explosive emergence of therapsids. The Middle of 30–96 mm. Our results confirm the alternate replace- Permian tetrapod record of the South African Karoo ment of the postcanines and the posterior migration of the Supergroup has the oldest advanced theriodonts, includ- postcanine series (including the loss without replacement ing gorgonopsians and therocephalians. The oldest of the anteriormost postcanines). Even when most of the therocephalians are the largest members of this lineage observations point to a posterior-to-anterior replacement and clearly were top predators in the Middle Permian. wave, the evidence is not clear-cut.