Strengthening Western Gondwanan correlations: A Brazilian Dicynodont (Synapsida,Anomodontia) in the Middle Triassic of Namibia |
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| Authors: | Fernando Abdala Claudia A Marsicano Roger MH Smith Roger Swart |
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| Institution: | 1. Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, P. Bag 3, WITS 2050, Johannesburg, South Africa;2. Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, IDEAN, CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina;3. Iziko SA Museum, P O Box 61, Cape Town 8000 and Department of Geological Sciences, University of Cape Town, P. Bag, Rondebosch 7701, South Africa;4. BlackGold Geosciences, P.O. Box 24287, Windhoek, Namibia |
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| Abstract: | Terrestrial Middle Triassic strata occur throughout continental Africa and are particularly well exposed in South Africa, Tanzania, Zambia, and Namibia. The youngest age for all these African deposits is widely accepted as early Middle Triassic (Anisian). Fossils collected recently from the uppermost strata of the upper Omingonde Formation in Namibia highlighted the presence of Chiniquodon, a carnivorous cynodont previously only found in Ladinian-Carnian aged rocks of South America. In addition, work in progress indicates that a large archosaur, originally reported as Erythrosuchus, also discovered from levels close to the top of this unit, is in fact a rauisuchian, a group of archosaurs well known from Ladinian-Carnian beds of southern South America. Here we present the first record of the tuskless dicynodont Stahleckeria potens from the top of the upper Omingonde Formation in central Namibia. This taxon was up until now only known from the Ladinian Dinodontosaurus Assemblage Zone of the Santa Maria Formation in southern Brazil. Thus, compelling evidence for a Ladinian age for the upper levels of the upper Omingonde Formation is provided by two therapsid and one archosaur taxa. The tetrapod fauna of the upper Omingonde Formation partially fills the gap of the well-documented hiatus (Ladinian gap), prevalent throughout the Karoo basins of south and central Africa. The presence of the same therapsid taxa in the Namibian Waterberg Basin and the Paraná Basin of Brazil during Middle Triassic suggests that these basins were biogeographically linked through a series of interconnecting lowlands, with no major ecological, climatic and/or physical barriers. |
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