Abstract
An exceptionally well-preserved specimen of the bauriid therocephalian Microgomphodon oligocynus from the Burgersdorp Formation (Early-Middle Triassic, Cynognathus Assemblage Zone) of the South African Karoo is described. In addition, a taxonomic revision of bauriid therocephalians from southern Africa, based on firsthand examination of almost all know specimens, is presented. Microgomphodon oligocynus and Bauria cynops are recognized as the only valid species of southern African bauriids. Microgomphodon oligocynus is differentiated from B. cynops on the basis of clear-cut morphological features such as the presence of a complete postorbital bar, pineal foramen, contribution of the vomer to the osseous secondary palate, comparatively large orbits, presence of a lateral fossa on the posterior portion of the horizontal ramus and on the coronoid process of the dentary, and reduced number of postcanines. Procrustes analysis of the two best-preserved specimens of these species allowed recognition of further shape differences: M. oligocynus has a taller but narrower cranium, taller snout, temporal opening more expanded laterally, pterygoid process located more anteriorly, and smaller suborbital vacuity. The mandible of M. oligocynus has a higher symphysis, relatively short corpus, and more laterally-directed coronoid process. Microgomphodon oligocynus is known from the Olenekian to what are probably late Anisian levels in South Africa and Namibia, whereas B. cynops is restricted to the early Anisian of South Africa.
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Acknowledgments
We are indebted to the curators of the collections mentioned in this study for access to the material. SAM-PK-K10160 was collected by R. M. H. Smith and Derik Wolvaardt. FA would especially like to thank Sheena Kaal from the Iziko-South African Museum for the loan of SAM-PK-K10160 and extended patience for its delayed return. Preparation of the specimen described and other studied specimens were made by Annelise Crean at the Iziko-South African Museum and A. Nthaopa Ntheri and Charlton Dube at the Bernard Price Institute, Johannesburg. FA is also very grateful to Jim Hopson for access to his notes and figures of bauriids and those of the late Dr. Christiane Mendrez-Carroll. Dr. Oliver Rauhut supplied photos of the type specimen of Watsoniella, and Dr. Christian Kammerer provided photos of bauriid specimens from the Smithsonian National Museum of Natural History, U.S. CT-scanning of the specimen was undertaken at the Helen Joseph Hospital (Johannesburg, South Africa) under the guidance of Jaymati Limbachia. We are thankful to Michael Day for his help to provide information for Fig. 13.11 and proofreading. The reviewers of this manuscript, Trond Sirgurdsen and Adam Huttenlocker, as well as the editor Christian Kammerer provided important suggestions that improved the final result of this work. The research of FA and BR research was funded by DST, NRF and PAST. TJ’s research was supported by the Claude Leon Foundation.
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Abdala, F., Jashashvili, T., Rubidge, B.S., van den Heever, J. (2014). New Material of Microgomphodon oligocynus (Eutherapsida, Therocephalia) and the Taxonomy of Southern African Bauriidae. In: Kammerer, C., Angielczyk, K., Fröbisch, J. (eds) Early Evolutionary History of the Synapsida. Vertebrate Paleobiology and Paleoanthropology. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-6841-3_13
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