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Ordovician (Arenig-Caradoc) Syntrophiidine brachiopods from the East Baltic Region
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology, Palaeontology group.
2005 (English)In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 48, no 4, 739-761 p.Article in journal (Refereed) Published
Abstract [en]

Syntrophiidine brachiopods are a rare and poorly known component of Ordovician Baltoscandian faunas. They appear in the East Baltic in the Billingenian (lower Arenig) as part of the earliest known benthic assemblages dominated by elements of the Palaeozoic Evolutionary Fauna. These faunal assemblages usually include bryozoans, ostracodes, and the earliest known porambonitoids, strophomenides and endopunctate orthides, such as Idiostrophia and Orthidium, which later became characteristic of the Whiterockian brachiopod assemblages in Laurentia, but by that time had disappeared from Baltica. The superfamily Syntrophioidea reappears in Baltoscandia in the mid Caradoc. In contrast, Porambonitoidea remained the integral part of the Baltoscandian brachiopod associations through the Ordovician. Porambonites, herein redefined on the basis of restudy of the type species P. intermedius, includes only smooth porambonitoids; taxa with the distinctive ornament of radiating rows of pits first appeared in the group in the mid Arenig. The taxa Eoporambonites gen. nov., Tetralobula peregrina sp. nov., Idiostrophia prima sp. nov. and Idiostrophia tenuicostata sp. nov. are erected.

Place, publisher, year, edition, pages
2005. Vol. 48, no 4, 739-761 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-91914DOI: 10.1111/j.1475-4983.2005.00487.xOAI: oai:DiVA.org:uu-91914DiVA: diva2:164794
Available from: 2004-05-14 Created: 2004-05-14 Last updated: 2013-06-14Bibliographically approved
In thesis
1. Ordovician (Billingen and Volkhov stages) Brachiopod Faunas of the East Baltic
Open this publication in new window or tab >>Ordovician (Billingen and Volkhov stages) Brachiopod Faunas of the East Baltic
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lower-Middle Ordovician (Arenig) successions in the East Baltic have been investigated for more than one hundred and fifty years. Nevertheless detailed sampling still yields new species and better knowledge of the environment in which these organisms lived. The successions are well suited for bed by bed sampling because of the lack of tectonic disturbance and because the sequences are well documented.

This study analyses collections of Billingen-Volkhov age mainly from the St. Petersburg region, but also from Estonia. A great deal of the material was obtained from the marly to clayey, soft sediment that intercalates the compact packstones and wackestones in the succession. Twenty-nine of these clay horizons were used for diversity estimates on the fauna through the succession. The most thoroughly investigated groups for this investigation were rhynchonelliformean brachiopods, conodonts and ostracodes. The results indicate that variances in diversity and abundance levels for these groups were not correlated, either to each other or to the small-scale sea level fluctuations that have been suggested for the region. However, diversity dynamics of brachiopods and ostracodes confirm the large-scale upward shallowing of the basin into the Upper Volkhov. Comparison with fossils from the limestones did not reveal any differences in faunal composition between the two preservation modes.

The detailed sampling, coupled with sampling of the recently described mud mounds that occur in several outcrops, yielded large numbers of specimens. This enabled revision of earlier poorly known rhynchonelliformean genera such as Ujukella Andreev, as well as better known genera such as Porambonites Pander. In total the examined faunas include 31 genera assigned to 53 species of rhynchonelliformean brachiopods. Of these Leoniorthis and Eoporambonites are defined as new genera, and the following new species are described: Neumania paucicostata, Ranorthis rotunda, Orthidium gambolovensis, Orthidium lavensis, Skenidioides minutus, Tetralobula peregrina, Idiostrophia prima and Idiostrophia tenuicostata.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 30 p.
Earth sciences, Early Middle Ordovician, Billingen Regional Stage, Volkhov Regional Stage, Diversity, Brachiopoda, Conodonta, Ostracoda, Estonia, Russia, Geovetenskap
National Category
Earth and Related Environmental Sciences
urn:nbn:se:uu:diva-4303 (URN)91-506-1756-7 (ISBN)
Public defence
2004-06-04, Lecture Theatre, Palaeontology building, Norbyvägen 22, SE-752 36 Uppsala, 13:00
Available from: 2004-05-14 Created: 2004-05-14 Last updated: 2011-02-17Bibliographically approved

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