Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships
The Hirnantian Glisstjärn Formation (Normalograptus persculptus graptolite Biozone) is a succession of limestones and shales onlapping the Katian Boda Limestone in the Siljan District, Sweden. It contains a conspicuous, up to several decimeter thick bed densely packed with bipolarly oriented, orthoc...
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| Format: | Article |
| Language: | English |
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Pensoft Publishers
2011-02-01
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| Series: | Fossil Record |
| Online Access: | https://fr.pensoft.net/article/30425/download/pdf/ |
| _version_ | 1797370075530919936 |
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| author | B. Kröger J. O. R. Ebbestad A. E. S. Högström Å. M. Frisk |
| author_facet | B. Kröger J. O. R. Ebbestad A. E. S. Högström Å. M. Frisk |
| author_sort | B. Kröger |
| collection | DOAJ |
| description | The Hirnantian Glisstjärn Formation (Normalograptus persculptus graptolite Biozone) is a succession of limestones and shales onlapping the Katian Boda Limestone in the Siljan District, Sweden. It contains a conspicuous, up to several decimeter thick bed densely packed with bipolarly oriented, orthoconic cephalopod conchs that can reach lengths of more than 120 cm. Conch fragmentation, bioereosion and the generally poor preservation of the conchs indicate time averaging and the conchs are tentatively interpreted as beached, and a result of winnowing. Ten nautiloid species were collected from the Glisstjärn Formation of which five are new: Dawsonoceras gregarium n. sp., Discoceras siljanense n. sp., Isorthoceras dalecarlense n. sp., Retizitteloceras rarum gen. et sp. n., and Transorthoceras osmundsbergense gen. et sp. n. The non-endemic taxa in most cases are known from elsewhere in Baltoscandia, except one species which is known from Siberia, and North America respectively. Proteocerid orthoceridans dominate the association, of which T. osmundsbergense is the predominant species. Oncocerids are diverse but together with tarphycerids very rare. Notable is the lack of many higher taxa, that are typical for other Late Ordovician shallow water depositional settings. Based on the taxonomical composition of the cephalopod mass occurrence it is interpreted as an indicator of eutrophication of the water masses in the area.doi:10.1002/mmng.201000014 |
| first_indexed | 2024-03-08T17:56:07Z |
| format | Article |
| id | doaj.art-5a796475f4f14267b4274750073ea43d |
| institution | Directory Open Access Journal |
| issn | 2193-0074 |
| language | English |
| last_indexed | 2024-03-08T17:56:07Z |
| publishDate | 2011-02-01 |
| publisher | Pensoft Publishers |
| record_format | Article |
| series | Fossil Record |
| spelling | doaj.art-5a796475f4f14267b4274750073ea43d2024-01-02T04:39:15ZengPensoft PublishersFossil Record2193-00742011-02-01141355310.1002/mmng.20100001430425Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationshipsB. Kröger0J. O. R. Ebbestad1A. E. S. Högström2Å. M. Frisk3Björn Kröger, Museum für Naturkunde der Humboldt-Universität, Invalidenstraße 43Museum of Evolution, Uppsala University, Norbyvägen 16Tromsø University Museum, Naharat SciencesDepartment of Earth Sciences, Palaeobiology, Villavägen 16The Hirnantian Glisstjärn Formation (Normalograptus persculptus graptolite Biozone) is a succession of limestones and shales onlapping the Katian Boda Limestone in the Siljan District, Sweden. It contains a conspicuous, up to several decimeter thick bed densely packed with bipolarly oriented, orthoconic cephalopod conchs that can reach lengths of more than 120 cm. Conch fragmentation, bioereosion and the generally poor preservation of the conchs indicate time averaging and the conchs are tentatively interpreted as beached, and a result of winnowing. Ten nautiloid species were collected from the Glisstjärn Formation of which five are new: Dawsonoceras gregarium n. sp., Discoceras siljanense n. sp., Isorthoceras dalecarlense n. sp., Retizitteloceras rarum gen. et sp. n., and Transorthoceras osmundsbergense gen. et sp. n. The non-endemic taxa in most cases are known from elsewhere in Baltoscandia, except one species which is known from Siberia, and North America respectively. Proteocerid orthoceridans dominate the association, of which T. osmundsbergense is the predominant species. Oncocerids are diverse but together with tarphycerids very rare. Notable is the lack of many higher taxa, that are typical for other Late Ordovician shallow water depositional settings. Based on the taxonomical composition of the cephalopod mass occurrence it is interpreted as an indicator of eutrophication of the water masses in the area.doi:10.1002/mmng.201000014https://fr.pensoft.net/article/30425/download/pdf/ |
| spellingShingle | B. Kröger J. O. R. Ebbestad A. E. S. Högström Å. M. Frisk Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships Fossil Record |
| title | Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships |
| title_full | Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships |
| title_fullStr | Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships |
| title_full_unstemmed | Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships |
| title_short | Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships |
| title_sort | mass concentration of hirnantian cephalopods from the siljan district sweden taxonomy palaeoecology and palaeobiogeographic relationships |
| url | https://fr.pensoft.net/article/30425/download/pdf/ |
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