End Ordovician extinctions:A coincidence of causes
The end Ordovician (Hirnantian) extinction was the first of the five big Phanerozoic extinction events, and the first that involved metazoan-based communities. It comprised two discrete pulses, both linked in different ways to an intense but short-lived glaciation at the South Pole. The first, occur...
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ftsydanskunivpub:oai:sdu.dk:publications/eef17d31-1ec4-4374-afb4-c43d71a39b85 2024-06-09T07:49:37+00:00 End Ordovician extinctions:A coincidence of causes Harper, David A. T. Hammarlund, Emma Rasmussen, Christian M. Ø. 2014-05 https://portal.findresearcher.sdu.dk/da/publications/eef17d31-1ec4-4374-afb4-c43d71a39b85 https://doi.org/10.1016/j.gr.2012.12.021 eng eng https://portal.findresearcher.sdu.dk/da/publications/eef17d31-1ec4-4374-afb4-c43d71a39b85 info:eu-repo/semantics/restrictedAccess Harper , D A T , Hammarlund , E & Rasmussen , C M Ø 2014 , ' End Ordovician extinctions : A coincidence of causes ' , Gondwana Research , vol. 25 , no. 4 , pp. 1294-1307 . https://doi.org/10.1016/j.gr.2012.12.021 article 2014 ftsydanskunivpub https://doi.org/10.1016/j.gr.2012.12.021 2024-05-14T23:53:18Z The end Ordovician (Hirnantian) extinction was the first of the five big Phanerozoic extinction events, and the first that involved metazoan-based communities. It comprised two discrete pulses, both linked in different ways to an intense but short-lived glaciation at the South Pole. The first, occurring at, or just below, the Normalograptus extraordinarius graptolite Biozone, mainly affected nektonic and planktonic species together with those living on the shallow shelf and in deeper water whereas the second, within the N. persculptus graptolite Biozone, was less focused, eradicating faunas across a range of water depths. In all about 85% of marine species were removed. Proposed kill mechanisms for the first phase have included glaciallyinduced cooling, falling sea level and chemical recycling in the oceans, but a general consensus is lacking. The second phase is more clearly linked to near-global anoxia associated with a marked transgression during the Late Hirnantian. Most recently, however, new drivers for the extinctions have been proposed, including widespread euxinia together with habitat destruction caused by plate tectonic movements, suggesting that the end Ordovician mass extinctions were a product of the coincidence of a number of contributing factors. Moreover, when the deteriorating climate intensified, causing widespread glaciation, a tipping point was reached resulting in catastrophe. Article in Journal/Newspaper South pole University of Southern Denmark Research Portal South Pole Gondwana Research 25 4 1294 1307 |
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University of Southern Denmark Research Portal |
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ftsydanskunivpub |
language |
English |
description |
The end Ordovician (Hirnantian) extinction was the first of the five big Phanerozoic extinction events, and the first that involved metazoan-based communities. It comprised two discrete pulses, both linked in different ways to an intense but short-lived glaciation at the South Pole. The first, occurring at, or just below, the Normalograptus extraordinarius graptolite Biozone, mainly affected nektonic and planktonic species together with those living on the shallow shelf and in deeper water whereas the second, within the N. persculptus graptolite Biozone, was less focused, eradicating faunas across a range of water depths. In all about 85% of marine species were removed. Proposed kill mechanisms for the first phase have included glaciallyinduced cooling, falling sea level and chemical recycling in the oceans, but a general consensus is lacking. The second phase is more clearly linked to near-global anoxia associated with a marked transgression during the Late Hirnantian. Most recently, however, new drivers for the extinctions have been proposed, including widespread euxinia together with habitat destruction caused by plate tectonic movements, suggesting that the end Ordovician mass extinctions were a product of the coincidence of a number of contributing factors. Moreover, when the deteriorating climate intensified, causing widespread glaciation, a tipping point was reached resulting in catastrophe. |
format |
Article in Journal/Newspaper |
author |
Harper, David A. T. Hammarlund, Emma Rasmussen, Christian M. Ø. |
spellingShingle |
Harper, David A. T. Hammarlund, Emma Rasmussen, Christian M. Ø. End Ordovician extinctions:A coincidence of causes |
author_facet |
Harper, David A. T. Hammarlund, Emma Rasmussen, Christian M. Ø. |
author_sort |
Harper, David A. T. |
title |
End Ordovician extinctions:A coincidence of causes |
title_short |
End Ordovician extinctions:A coincidence of causes |
title_full |
End Ordovician extinctions:A coincidence of causes |
title_fullStr |
End Ordovician extinctions:A coincidence of causes |
title_full_unstemmed |
End Ordovician extinctions:A coincidence of causes |
title_sort |
end ordovician extinctions:a coincidence of causes |
publishDate |
2014 |
url |
https://portal.findresearcher.sdu.dk/da/publications/eef17d31-1ec4-4374-afb4-c43d71a39b85 https://doi.org/10.1016/j.gr.2012.12.021 |
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South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_source |
Harper , D A T , Hammarlund , E & Rasmussen , C M Ø 2014 , ' End Ordovician extinctions : A coincidence of causes ' , Gondwana Research , vol. 25 , no. 4 , pp. 1294-1307 . https://doi.org/10.1016/j.gr.2012.12.021 |
op_relation |
https://portal.findresearcher.sdu.dk/da/publications/eef17d31-1ec4-4374-afb4-c43d71a39b85 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.gr.2012.12.021 |
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Gondwana Research |
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25 |
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4 |
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1294 |
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1307 |
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