The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia
Bryozoans from the Dapingian (Middle Ordovician) of the Baltic paleobasin remain poorly studied and their taxonomic composition is unclear. In this paper, three bryozoan taxa, a bifoliate cystoporate Planopora volkhovensis n. gen. n. sp., a trepostome Hemiphragma insolitum n. sp., and an esthoniopor...
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ftbioone:10.1017/jpa.2020.73 2024-06-02T08:11:54+00:00 The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia Anna V. Koromyslova Petr V. Fedorov Anna V. Koromyslova Petr V. Fedorov world 2020-12-31 text/HTML https://doi.org/10.1017/jpa.2020.73 en eng The Paleontological Society doi:10.1017/jpa.2020.73 All rights reserved. https://doi.org/10.1017/jpa.2020.73 Text 2020 ftbioone https://doi.org/10.1017/jpa.2020.73 2024-05-07T00:47:45Z Bryozoans from the Dapingian (Middle Ordovician) of the Baltic paleobasin remain poorly studied and their taxonomic composition is unclear. In this paper, three bryozoan taxa, a bifoliate cystoporate Planopora volkhovensis n. gen. n. sp., a trepostome Hemiphragma insolitum n. sp., and an esthonioporate Esthoniopora clara Koromyslova, are described from Dapingian deposits of an unusual clayey-calcareous Hecker-type mudmound on the right bank of the Volkhov River in Leningrad Oblast', north-western Russia. Combined X-ray microtomography, scanning electron microscopy, and light microscopy of thin sections were used to characterize their morphology. Analysis of the stratigraphic distribution of early cystoporate bryozoans suggests that Planopora n. gen. is the oldest cystoporate bryozoan with an erect, bifoliate colony. The growth modes of these bryozoans are discussed. The colonies of P. volkhovensis n. gen. n. sp. and E. clara have an attachment structure, a holdfast, at their base, probably indicating their attachment to sponge spicules. The bryozoan H. insolitum n. sp. produced rod-like colonies, formed by overgrowing the problematic tubular fossil Sphenothallus Hall. It can be assumed that sponges with unfused siliceous spicules and individuals of Sphenothallus were numerous on the surface of the mudmound during its formation and provided a suitable substrate for settlement of bryozoan larvae. Text North-Western Russia BioOne Online Journals Holdfast ENVELOPE(-66.590,-66.590,-66.803,-66.803) Journal of Paleontology 95 1 24 39 |
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BioOne Online Journals |
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ftbioone |
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English |
description |
Bryozoans from the Dapingian (Middle Ordovician) of the Baltic paleobasin remain poorly studied and their taxonomic composition is unclear. In this paper, three bryozoan taxa, a bifoliate cystoporate Planopora volkhovensis n. gen. n. sp., a trepostome Hemiphragma insolitum n. sp., and an esthonioporate Esthoniopora clara Koromyslova, are described from Dapingian deposits of an unusual clayey-calcareous Hecker-type mudmound on the right bank of the Volkhov River in Leningrad Oblast', north-western Russia. Combined X-ray microtomography, scanning electron microscopy, and light microscopy of thin sections were used to characterize their morphology. Analysis of the stratigraphic distribution of early cystoporate bryozoans suggests that Planopora n. gen. is the oldest cystoporate bryozoan with an erect, bifoliate colony. The growth modes of these bryozoans are discussed. The colonies of P. volkhovensis n. gen. n. sp. and E. clara have an attachment structure, a holdfast, at their base, probably indicating their attachment to sponge spicules. The bryozoan H. insolitum n. sp. produced rod-like colonies, formed by overgrowing the problematic tubular fossil Sphenothallus Hall. It can be assumed that sponges with unfused siliceous spicules and individuals of Sphenothallus were numerous on the surface of the mudmound during its formation and provided a suitable substrate for settlement of bryozoan larvae. |
author2 |
Anna V. Koromyslova Petr V. Fedorov |
format |
Text |
author |
Anna V. Koromyslova Petr V. Fedorov |
spellingShingle |
Anna V. Koromyslova Petr V. Fedorov The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia |
author_facet |
Anna V. Koromyslova Petr V. Fedorov |
author_sort |
Anna V. Koromyslova |
title |
The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia |
title_short |
The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia |
title_full |
The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia |
title_fullStr |
The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia |
title_full_unstemmed |
The oldest bifoliate cystoporate and two other bryozoan taxa from the Dapingian (Middle Ordovician) of north-western Russia |
title_sort |
oldest bifoliate cystoporate and two other bryozoan taxa from the dapingian (middle ordovician) of north-western russia |
publisher |
The Paleontological Society |
publishDate |
2020 |
url |
https://doi.org/10.1017/jpa.2020.73 |
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world |
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ENVELOPE(-66.590,-66.590,-66.803,-66.803) |
geographic |
Holdfast |
geographic_facet |
Holdfast |
genre |
North-Western Russia |
genre_facet |
North-Western Russia |
op_source |
https://doi.org/10.1017/jpa.2020.73 |
op_relation |
doi:10.1017/jpa.2020.73 |
op_rights |
All rights reserved. |
op_doi |
https://doi.org/10.1017/jpa.2020.73 |
container_title |
Journal of Paleontology |
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95 |
container_issue |
1 |
container_start_page |
24 |
op_container_end_page |
39 |
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1800758182171115520 |