New findings of the genus Revalotrypa, the oldest bryozoan genus of Baltoscandia, in north-western Russia

New findings of esthonioporate bryozoans of the species Revalotrypa cf. inopinata, representing one of the oldest bryozoans of Baltoscandia, are described from an outcrop located in Leningrad Oblast' (north-western Russia). The colonies of this species are very small and were extracted from lim...

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Bibliographic Details
Published in:Carnets de géologie (Notebooks on geology)
Main Authors: Fedorov, Petr V., Koromyslova, Anna V.
Format: Article in Journal/Newspaper
Language:English
Published: Association "Carnets de Géologie" 2019
Subjects:
Bryozoa
Ordovician
Floian
Baltoscandia
micro-CT
Bryozoaires
Ordovicien
Floïen
Baltoscandie
microtomographie
Nord-ouest de la Russie
North-Western Russia
Online Access:http://hdl.handle.net/2042/70296
https://doi.org/10.4267/2042/70296
Description
Summary:New findings of esthonioporate bryozoans of the species Revalotrypa cf. inopinata, representing one of the oldest bryozoans of Baltoscandia, are described from an outcrop located in Leningrad Oblast' (north-western Russia). The colonies of this species are very small and were extracted from limestone-cemented nodules found in glauconitic sandstones of the lower part of the Joa Member (Paroistodus proteus conodont zone, lowermost Floian, Lower Ordovician). Combined X-ray microtomography and the examination of traditional thin sections under a stereomicroscope and a light microscope were used to study the morphology of this species. Les nouvelles découvertes de bryozoaires esthonioporates de l'espèce Revalotrypa cf. inopinata, représentant l'un des plus anciens bryozoaires de Baltoscandie, sont décrites dans un affleurement situé dans l'oblast de Léningrad (nord-ouest de la Russie). Les colonies de cette espèce sont très petites et furent extraites de nodules calcaires cimentés trouvés dans les grès glauconitiques de la partie inférieure du Membre Joa (zone de сonodonte Paroistodus proteus, Floïen basal, Ordovicien inférieur). La microtomographie à rayons X combinée et l'examen de coupes minces traditionnelles au stéréomicroscope et au microscope optique sont utilisés pour étudier la morphologie de cette espèce.

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