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Cymraeg

Taxonomic diversity of Cambrian brachiopods from the Middle East

Staff: M.G. Bassett and L.E. Popov

Introduction

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Exposures of the Lower to Middle Cambrian sedimentary rocks in the Timna National Park, southern Negev desert, Israel. The area which holds one of the oldest cooper mines, more than 4000 thousand years old is also famous for the unique localities of silicified early Mid Cambrian rhynchonelliformean brachiopods.
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Silicified shells of Psiloria dayi Cooper from the early Mid Cambrian of east Dead Sea coast, Jordan show in fine details a primitive articulation with paired teeth in the ventral valve, but without sockets in the dorsal valve.

The recently revised phylogeny of the higher brachiopod taxa recognises that several problematic groups of Cambrian calcareous-shelled stocks (obolellids, kutorgenids, chileids) and Palaeozoic dictyonellids may possibly belong to the "articulate" clade; this is a view partly based on new data from our completed study together with Prof. Lars Holmer (Uppsala University). A new unique collection of the Early and Middle Cambrian silicified clacareous shelled brachiopods from Middle East, Central Asia, Greenland and Australia, together with some old collections deposited in British and American museums provides a good foundation for a fundamental taxonomic revision of these enigmatic early brachiopods.

This study almost entirely based on extensive collection sampled from the Lower to Middle Cambrian deposits exposed along the western Dead Sea coast in Jordan and in the Timna National Park in southern Negev desert, Israel. This collection is unique in abundance and diversity of the early rhynchonelliformean brachiopods. Most of the shells are silicified, which makes possible to dissolve them from the carbonate rock applying acetic and formic acids. This fauna, which is in advanced state of the study, will give new information on the origin, phylogeny and functional morphology of the early brachiopods with calcareous mineralisation of the shell (Bassett et al.2001).

References

Bassett, M. G., Popov, L. E. and Holmer, L. E. 2001. Functional morphology of articulatory structures and implications for patterns of musculature in Cambrian rhynchonelliform brachiopods. In: In: Brunton, C. H., Cocks L. R. M. and Long, S. L. (eds) Brachiopods past and present. Systematic Association Special Volume Series, 63, 163-176.