Diversification patterns in the clitambonitoid brachiopods of the Ordovician of Baltoscandia (original) (raw)
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Resolving early Mid-Ordovician (Kundan) bioevents in the East Baltic based on brachiopods
Geobios, 2008
Bed-by-bed sampling of brachiopods from selected Kundan Stage localities in the East Baltic has permitted the construction of a-diversity curves, unprecedented in detail from this particular stage and region. These a-diversity curves can be correlated between the investigated sections, along an east to west transect of some 200 km and indicate bioevents associated with intervals of increased palaeo-water depth. The highest peaks in a-diversity occur when biofacies analysis and sedimentological evidence indicate drowning events. The events involve mainly taxa endemic to the Baltic province at this time and thus, the radiation proceeded by a modest expansion of the brachiopod fauna into deeper-water environments, isolated at this time from major immigrations. In addition to increased a-diversity, b-diversity was signalled by new, deeper-water communities and the isolation of the province helped retain high values of g-diversity. # 2008 Elsevier Masson SAS. All rights reserved. Résumé L'échantillonnage niveau par niveau de brachiopodes dans une sélection de localités de l'Étage de Kundan dans l'Est de la Baltique a permis d'établir des courbes de diversité de niveau a d'une précision inégalée pour cet Étage et cette région. Ces courbes de diversité de niveau a peuvent être corrélées entre les différentes coupes étudiées selon un axe est-ouest sur une distance d'environ 200 km. Elles mettent alors en évidence des bio-événements associés à des intervalles de temps durant lesquels on observe une augmentation de la paléoprofondeur. Les pics de diversité maximum au niveau a sont liés à des approfondissements du milieu, démontrés par des analyses sédimentologiques et des biofaciès. Ces évènements concernent essentiellement des taxons endémiques à la province baltique à cette époque. On observe une modeste expansion des faunes de brachiopodes dans les environnements plus profonds, isolés à cette époque de toute immigration importante. En plus d'une augmentation de la diversité de niveau a, la diversité de niveau b se signale par de nouvelles communautés d'eau profonde et l'isolement de la province a permis de garder une importante diversité de niveau g.
Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 2007
ABSTRACTTwo Ordovician plectambonitoid genera, Alwynella and Grorudia, occur in drill core sections of Latvia in the East Baltic, and in exposures and loose blocks on the Swedish Island of Öland in the Baltic Sea. The new material confirms differences between the two taxa that are assigned herein to separate families, Alwynellidae fam. nov. and Grorudiidae Cocks & Rong, 1989. In particular, the undercut cardinalia separates Alwynella from Grorudia and indicates its proximity to the sowerbyellids. The genus Grorudia, which is externally similar to Alwynella, is more closely related to the palaeostrophomenines. A new species Grorudia morrisoni sp. nov. is established in the East Baltic. The specimens from Öland are included tentatively within the genus Grorudia due to lack of interiors. Both Alwynella and Grorudia were confined to deeper-water facies in the Baltic palaeobasin, within successions ranging in age from latest Mid (late Llanvirn) to earliest Late Ordovician (mid Caradoc).
ORDOVICIAN (ARENIG-CARADOC) SYNTROPHIIDINE BRACHIOPODS FROM THE EAST BALTIC REGION
Palaeontology, 2005
Abstract: 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.
Acta Palaeontologica Polonica, 2006
The brachiopod faunas from deposits recording the Early-Middle Frasnian transition of Poland are poorly known. The present report describes these faunas that were recovered from Wietrznia and Kostomłoty (Holy Cross Moun− tains) and Dębnik (Silesian−Cracow Upland) regions positioned on the southern Polish carbonate shelf. The brachio− pod distribution was analysed relative to a significant d 13 C excursion, referred recently to as Palmatolepis punctata Event. The sporadic occurrence of brachiopods at Dębnik makes it difficult to analyse the biotic response to this geo− chemical anomaly. However, higher brachiopod frequency in the topmost part of the section coincides with a gradual decrease of d 13 C down to the Frasnian background values. At two studied sections at Wietrznia the greatest taxonomic diversity and abundance of brachiopods (Flabellulirostrum-Coeloterorhynchus assemblage) are confined to the Pal− matolepis transitans Zone. In the following Pa. punctata Zone brachiopods are rare (Biernatella lentiformis assem− blage) or absent, which suggests a serious deterioration of the environmental conditions linked probably with periods of benthic anoxia−dysoxia and oligotrophic conditions in the basin. In two Kostomłoty sections brachiopods faunas of this age are members of the mostly monospecific rhynchonellid−dominated Phlogoiderhynchus polonicus assem− blage which inhabited deeper−water environments characteristic of intrashelf oxygen−depleted basins of Łysogóry− Kostomłoty region. In some horizons large shells of P. polonicus were frequently colonised by discinoid Romerella? sp. Among 28 species described in this report new forms include: Flabellulirostrum kielcensis sp. nov., F. rackii sp. nov., and Thomasaria ventosa sp. nov.
Geological Magazine, 2009
A detailed ecostratigraphical framework is established for the lower Middle Ordovician Kundan regional stage of the East Baltic area corresponding to the Asaphus expansus, A. raniceps and A. eichwaldi trilobite zones (lower Darriwilian). The study is based on approximately 6200 brachiopods collected bed by bed from limestone sections in northern Estonia (Harku Trench and Saka) and western Russia (Putilovo Quarry, Lava River canyon and Lynna River valley) with, in addition, the first detailed systematic assessment of the Kundan brachiopods of the East Baltic. These sections represent an oblique depth transect some 400 kilometres long, deepening eastwards. Five biofacies associations have been recognized using detrended correspondence and cluster analyses: a shallow-water Lycophoria association, a transitional Gonambonites association and two deeper-water associations, the soft-substrate Orthis callactis and the hard-substrate Orthambonites associations. A separate, fifth soft-substra...
Inarticulate brachiopods around the Middle-Upper Ordovician boundary in Vastergotland
Gff, 1986
Ifolmer, L. E., 19860701: Inarticulate brachiopods around the hfiddfe-Upper Ordovician boundary in .VSstergBtland. Geologkka Ffireningerrr i Srockholrii Fiirliandlingar, Vol. 10s. Pt. 2, pp. 97-126. Stockholm. ISSN 0016-786X. Inarticulate brachiopods are described from the Upper Viruan (hiiddle Ordovician) and Lower Harjuan (Upper Ordovician) limestones in Gullhogen quarry, Viistergotland, southern Sweden. Sixteen species of inarticulate brachiopods (seven named, six of which are new) are assigned to 14 genera (13 named, one of which is new). The lingulids are treated under open nomenclature. One new acrotretacean genus (Rhiriorrera) is described as are the acrotretacean species Hkirrgerella feniris, Coriotrera? orbicdarir, Veliseprirrn srricrrori, Rhirrorreta rriiiscularb, Toryrielasrria? currata and T.? plaria. The stratigraphy of the hiiddle-Upper Ordovician boundary interval in Viistergotland is briefly discussed. 0 Bracliiopoda, lriarticrclata, Acrorreracea, riew genus, Rhinotreta, biosrrarigraphy, Middle-Upper Ordoriciari boundary, Grrllliiigeri quarry, Vas/ergorlarrd,