Change search
ReferencesLink to record
Permanent link

Direct link
Paterimitra pyramidalis from South Australia: Scleritome, shell structure and evolution of a lower Cambrian stem group brachiopod
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
Show others and affiliations
2014 (English)In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 57, no 2, 417-446 p.Article in journal (Refereed) Published
Abstract [en]

The tommotiid Paterimitra pyramidalis Laurie, 1986, is redescribed based on well-preserved material from the lower Cambrian Wilkawillina, Wirrapowie and Ajax limestones of the Flinders Ranges, South Australia. The material shows that the scleritome of Paterimitra pyramidalis includes three sclerite morphotypes (S1, S2 and L). Detailed shell microstructure studies show striking similarities with both the paterinid brachiopod Askepasma toddense and the tommotiid Eccentrotheca helenia, which strengthens the suggested evolutionary link between tommotiids and brachiopods. Based on the partly articulated specimens and similarities in shell microstructure and sclerite morphology with Eccentrotheca, Paterimitra pyramidalis is reconstructed as a tube-dwelling, epifaunal, sessile, filter-feeder with an organic pedicle-like attachment structure. The proposed reconstruction of the scleritome comprises a basal unit composed of one S1 and one S2 sclerite, as well as an unresolved number of L sclerites lining a coniform tubular structure.

Place, publisher, year, edition, pages
2014. Vol. 57, no 2, 417-446 p.
Keyword [en]
Tommotiida, Brachiopoda, Paterimitra, scleritome structure, lower Cambrian, South Australia
National Category
Geology Other Earth and Related Environmental Sciences Evolutionary Biology
Research subject
Earth Science with specialization in Historical Geology and Palaeontology
URN: urn:nbn:se:uu:diva-180191DOI: 10.1111/pala.12072OAI: diva2:548683
Available from: 2012-08-31 Created: 2012-08-31 Last updated: 2015-02-02Bibliographically approved
In thesis
1. Early Cambrian Problematic Lophotrochozoans and Dilemmas of Scleritome Reconstructions
Open this publication in new window or tab >>Early Cambrian Problematic Lophotrochozoans and Dilemmas of Scleritome Reconstructions
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The emergence and radiation of metazoan body plans around the Precambrian/Cambrian boundary, some 500-600 million years ago, seems to be concordant with the appearance and diversification of preservable hard parts. Several Precambrian soft-bodied, multicellular organisms most likely represent stem-group bilaterians, but their fossil record is rather sparse.  In contrast, the Cambrian fossil record is comparably rich – comprising hard part, trace fossil and delicate soft tissue preservation – and most animal phyla that we know of today had evolved by the end of the Cambrian. Consequently, this time represents an important period in the early evolution of metazoan life forms. Most skeletal remnants of invertebrate organisms from this period are preserved in incomplete, disarticulated sclerite assemblages, and the true architecture of the original skeletal structure, the scleritome, may therefore be hard to discern. Many scleritomous taxa have been suggested to be members of the lophotrochozoan clade, while their exact position within this group remains unclear. Such taxa are often referred to as Problematica. This thesis deals with some problematic scleritomous early Cambrian lophotrochozoans, and as such also addresses the dilemmas of scleritome reconstructions. In the first part, completely disarticulated calcareous sclerites from the lower Cambrian of North Greenland are described as Trachyplax arctica. Hypothetical scleritome reconstruction alternatives and comparisons to other scleritome-bearing taxa are discussed, but the lack of articulated material obscures any satisfactory conclusions regarding phylogenetic affinities and the original morphology of the organism. The other part of the thesis focuses on some minute, organophosphatic scleritomous metazoans, tommotiids, found in lower Cambrian limestone successions in South Australia – Paterimitra pyramidalis and Kulparina rostrata – their scleritome architecture and their phylogenetic relationship with paterinid brachiopods. The oldest brachiopod from South Australia, Askepasma saproconcha, and the slightly younger Askepasma toddense are also described and discussed. Based on articulated specimens, recently described partial scleritomes of the tommotiid Eccentrotheca helenia and similarities in shell ultrastructure with both Eccentrotheca and Askepasma, Paterimitra is interpreted as a stem-group brachiopod and reconstructed as a bilaterally symmetrical, sessile, filter feeder with a tubular/conical scleritome. The morphological similarities with Paterimitra point in the same direction for the slightly older Kulparina.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 47 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 967
Problematica, scleritome, Trachyplax, tommotiid, Cambrian, South Australia, North Greenland
National Category
Geology Other Earth and Related Environmental Sciences Evolutionary Biology
Research subject
Earth Science with specialization in Historical Geology and Palaeontology
urn:nbn:se:uu:diva-180195 (URN)978-91-554-8462-0 (ISBN)
Public defence
2012-10-19, Hambergsalen, Geocentrum, Villavägen 16, Uppsala, 09:00 (English)
Available from: 2012-09-27 Created: 2012-08-31 Last updated: 2013-01-23Bibliographically approved

Open Access in DiVA

fulltext(5581 kB)71 downloads
File information
File name FULLTEXT01.pdfFile size 5581 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Larsson, Cecilia MHolmer, Lars E
By organisation
In the same journal
GeologyOther Earth and Related Environmental SciencesEvolutionary Biology

Search outside of DiVA

GoogleGoogle Scholar
Total: 71 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 227 hits
ReferencesLink to record
Permanent link

Direct link