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A stem group brachiopod from the Lower Cambrian - support for a Micrina (Halkieriid) ancestry.
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
Uppsala University.
University of Glasgow, UK.
2002 (English)In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 45, no 5, 875-882 p.Article in journal (Refereed) Published
Abstract [en]

The shell structure of the Lower Cambrian Mickwitzia, a bilaterally symmetrical bivalve hitherto doubtfully assigned to the Brachiopoda, confirms that the genus shares characters with linguliform brachiopods. The columnar lamination of its organophosphatic shell is homologous with that characterizing acrotretides. The shell, however, is also pervaded by striated apatitic tubes indistinguishable from those permeating the sclerites of the problematic organophosphatic, laminar–shelled Micrina which is close to Halkieria. No crown group brachiopods have such tubes that are presumed to have contained setae. The presence of both these features in the Mickwitzia shell suggests that the stock is a stem group brachiopod with a halkieriid ancestry.

Place, publisher, year, edition, pages
2002. Vol. 45, no 5, 875-882 p.
Keyword [en]
stem group brachiopod, brachiopod ancestry, halkieriid–brachiopod lineage
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:uu:diva-91213DOI: 10.1111/1475-4983.00265OAI: oai:DiVA.org:uu-91213DiVA: diva2:163870
Available from: 2003-12-15 Created: 2003-12-15 Last updated: 2013-04-08Bibliographically approved
In thesis
1. The Early Cambrian Fauna of North-East Greenland
Open this publication in new window or tab >>The Early Cambrian Fauna of North-East Greenland
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Den tidigkambriska faunan från Nordöstgrönland
Abstract [en]

Small shelly fossils are common in sediments of Early Cambrian age and include the earliest common representatives of metazoan animals with mineralized hard parts. The group includes fossils of very different morphology, composition and ultrastructure. They seem to represent skeletal remains of numerous animal groups, the biological affinities of which are largely unresolved. However, the wide geographic range of many forms has the potential to enhance biostratigraphic and palaeogeographic resolution in the Early Cambrian.

The late Early Cambrian sequence of North-East Greenland has yielded an assemblage of more than 88 species of small shelly fossils, brachiopods and trilobites, indicative of a middle Dyeran age (Botoman equivalent). The recovered fossils include a number of species that are known from other Early Cambrian palaeocontinents, and particularly strong ties to late Early Cambrian faunas of Australia are documented. The many cosmopolitan taxa thus identified suggests a close juxtaposition of palaeocontinents at this time.

The systematic affinity of many of these small shelly fossils is poorly understood, partly because of their fragmentary nature and poor preservation. However, new data from North-East Greenland improves our understanding of the function and biological affinity of certain taxa. Collections of the problematic fossil Mongolitubulus from North and North-East Greenland exhibit characters indicative of a defensive function as spines of bivalved arthropods, while species of the problematic genus Triplicatella represent the opercula of an unknown tubular shell, probably related to orthothecid hyoliths. The bivalved fossil Mickwitzia from North-East Greenland combines characters of linguliform brachiopods and sclerites of Micrina, a non-bivalved problematic form (halkieriid) from Australia. The combination suggests that Mickwitzia is a stem group brachiopod and strengthens arguments for a halkieriid ancestry of the brachiopod phylum.

Place, publisher, year, edition, pages
Uppsala: Institutionen för geovetenskaper, 2003. 22 p.
Earth sciences, Early Cambrian, Dyeran, Botoman, Biostratigraphy, Palaeogeography, Small Shelly Fossils, Brachiopoda, Mollusca, Hyolitha, Trilobita, Geovetenskap
National Category
Earth and Related Environmental Sciences
urn:nbn:se:uu:diva-3910 (URN)91-506-1731-1 (ISBN)
Public defence
2004-01-16, Föreläsningssalen, Paleontologiska museet, Norbyvägen 22, Uppsala, 13:00
Available from: 2003-12-15 Created: 2003-12-15Bibliographically approved

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Holmer, Lars E.Skovsted, Christian B.
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