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1 March 2013 The Oldest Brachiopods from the Lower Cambrian of South Australia
Timothy P. Topper, Lars E. Holmer, Christian B. Skovsted, Glenn A. Brock, Uwe Balthasar, Cecilia M. Larsson, Sandra Pettersson Stolk, David A.T. Harper
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Abstract

The morphology and organophosphatic shell structure of the paterinate brachiopod Askepasma is documented using new and previously collected specimens from the lower Cambrian of South Australia. Lack of adequately preserved material has seen the majority of paterinate specimens previously reported from South Australia referred to the genus Askepasma and treated under open nomenclature. Large collections of paterinates from the lower Cambrian Wilkawillina, Ajax, and Wirrapowie limestones in the Arrowie Basin, South Australia have prompted redescription of the type species Askepasma toddense and the erection of a new species, Askepasma saproconcha sp. nov. Askepasma saproconcha sp. nov. currently represents the oldest known brachiopod from the lower Cambrian successions in South Australia with a FAD in pre-trilobitic (Terreneuvian, Cambrian Stage 2, lower Atdabanian) strata in the basal part of the Wilkawillina and Wirrapowie limestones. Askepasma toddense predominantly occurs in Abadiella huoi Zone equivalent strata (Unnamed Cambrian Series 2, Stage 3, middle-upper Atdabanian) in the upper part of the lower Wilkawillina, Wirrapowie, and Ajax limestones. The shell microstructure of Askepasma suggests a proximal stem group position within the Brachiopoda and similarities with tommotiid taxa provides further evidence that the ancestry of crown group brachiopods is firmly entrenched within the Tommotiida.

Copyright © 2013 T.P. Topper et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Timothy P. Topper, Lars E. Holmer, Christian B. Skovsted, Glenn A. Brock, Uwe Balthasar, Cecilia M. Larsson, Sandra Pettersson Stolk, and David A.T. Harper "The Oldest Brachiopods from the Lower Cambrian of South Australia," Acta Palaeontologica Polonica 58(1), 93-109, (1 March 2013). https://doi.org/10.4202/app.2011.0146
Received: 16 September 2011; Accepted: 15 November 2011; Published: 1 March 2013
KEYWORDS
Arrowie Basin
Askepasma
Brachiopoda
Flinders Ranges
lower Cambrian
microstructure
Paterinida
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