Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae)
Background and aims – The majority of freshwater diatom lineages appear to have evolved before or during the Eocene, with rapid radiation occurring in the Miocene. However, only a few accurately dated fossil localities are available to test this assertion, resulting in an overall poor understanding...
Published in: | Plant Ecology and Evolution |
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Meise Botanic Garden and Royal Botanical Society of Belgium
2010
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Online Access: | https://doi.org/10.5091/plecevo.2010.419 https://plecevo.eu/article/32421/ https://plecevo.eu/article/32421/download/pdf/ |
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ftpensoft:10.5091/plecevo.2010.419 2024-09-15T18:26:40+00:00 Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae) Siver,Peter Wolfe,Alexander Edlund,Mark 2010 text/html https://doi.org/10.5091/plecevo.2010.419 https://plecevo.eu/article/32421/ https://plecevo.eu/article/32421/download/pdf/ en eng Meise Botanic Garden and Royal Botanical Society of Belgium info:eu-repo/semantics/altIdentifier/eissn/2032-3921 info:eu-repo/semantics/altIdentifier/pissn/2032-3913 info:eu-repo/semantics/openAccess All Rights Reserved Plant Ecology and Evolution 143(3): 340-351 ACTINELLA EOCENE FOSSIL DIATOMS FRESHWATER NUPELA OXYNEIS RAPHE Regular Paper 2010 ftpensoft https://doi.org/10.5091/plecevo.2010.419 2024-06-24T03:56:04Z Background and aims – The majority of freshwater diatom lineages appear to have evolved before or during the Eocene, with rapid radiation occurring in the Miocene. However, only a few accurately dated fossil localities are available to test this assertion, resulting in an overall poor understanding of the biostratigraphy and early evolution of these organisms. Exquisitely preserved diatoms have been uncovered from Eocene lake sediments deposited post-eruptively in the Giraffe kimberlite pipe (Northwest Territories, Canada). We describe three new pennate diatoms from this deposit and discuss their evolutionary implications. Methods – Both oxidized preparations and whole-rock mudstone samples from the Giraffe Pipe core were examined with light and scanning electron microscopy for diatom remains. Key results – Species belonging to the genera Actinella F.W.Lewis, Oxyneis Round and Nupela Vyverman & Compère are described from the Giraffe Pipe sediments. Oxyneis apporrecta is a unique species with valves that are centrally constricted, inflations midway between the center and apices, and protracted and rostrate apices. Actinella giraffensis is a small taxon that lacks a highly complex head pole, and is most closely related to a species known today only from the highlands of New Zealand. Nupela mutabilis has variably shaped valves possessing a raphe and unique areolae characteristic of this genus. These findings represent the first known fossils for both Oxyneis and Nupela, and the oldest record for Actinella. Conclusions – None of the species are known from extant floras and are therefore considered extinct. However, the morphological features they present, including the structure of the areolae, raphe, rimoportula and girdle bands, share pronounced affinities with modern congeneric taxa. The well-developed raphe found on Nupela mutabilis confirms that the evolution of this structure dates to at least the Middle Eocene, and supports the hypothesis that it may be older than the Paleocene. Report Northwest Territories Pensoft Publishers Plant Ecology and Evolution 143 3 340 351 |
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Pensoft Publishers |
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ftpensoft |
language |
English |
topic |
ACTINELLA EOCENE FOSSIL DIATOMS FRESHWATER NUPELA OXYNEIS RAPHE |
spellingShingle |
ACTINELLA EOCENE FOSSIL DIATOMS FRESHWATER NUPELA OXYNEIS RAPHE Siver,Peter Wolfe,Alexander Edlund,Mark Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae) |
topic_facet |
ACTINELLA EOCENE FOSSIL DIATOMS FRESHWATER NUPELA OXYNEIS RAPHE |
description |
Background and aims – The majority of freshwater diatom lineages appear to have evolved before or during the Eocene, with rapid radiation occurring in the Miocene. However, only a few accurately dated fossil localities are available to test this assertion, resulting in an overall poor understanding of the biostratigraphy and early evolution of these organisms. Exquisitely preserved diatoms have been uncovered from Eocene lake sediments deposited post-eruptively in the Giraffe kimberlite pipe (Northwest Territories, Canada). We describe three new pennate diatoms from this deposit and discuss their evolutionary implications. Methods – Both oxidized preparations and whole-rock mudstone samples from the Giraffe Pipe core were examined with light and scanning electron microscopy for diatom remains. Key results – Species belonging to the genera Actinella F.W.Lewis, Oxyneis Round and Nupela Vyverman & Compère are described from the Giraffe Pipe sediments. Oxyneis apporrecta is a unique species with valves that are centrally constricted, inflations midway between the center and apices, and protracted and rostrate apices. Actinella giraffensis is a small taxon that lacks a highly complex head pole, and is most closely related to a species known today only from the highlands of New Zealand. Nupela mutabilis has variably shaped valves possessing a raphe and unique areolae characteristic of this genus. These findings represent the first known fossils for both Oxyneis and Nupela, and the oldest record for Actinella. Conclusions – None of the species are known from extant floras and are therefore considered extinct. However, the morphological features they present, including the structure of the areolae, raphe, rimoportula and girdle bands, share pronounced affinities with modern congeneric taxa. The well-developed raphe found on Nupela mutabilis confirms that the evolution of this structure dates to at least the Middle Eocene, and supports the hypothesis that it may be older than the Paleocene. |
format |
Report |
author |
Siver,Peter Wolfe,Alexander Edlund,Mark |
author_facet |
Siver,Peter Wolfe,Alexander Edlund,Mark |
author_sort |
Siver,Peter |
title |
Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae) |
title_short |
Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae) |
title_full |
Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae) |
title_fullStr |
Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae) |
title_full_unstemmed |
Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant genera Oxyneis, Actinella and Nupela (Bacillariophyceae) |
title_sort |
taxonomic descriptions and evolutionary implications of middle eocene pennate diatoms representing the extant genera oxyneis, actinella and nupela (bacillariophyceae) |
publisher |
Meise Botanic Garden and Royal Botanical Society of Belgium |
publishDate |
2010 |
url |
https://doi.org/10.5091/plecevo.2010.419 https://plecevo.eu/article/32421/ https://plecevo.eu/article/32421/download/pdf/ |
genre |
Northwest Territories |
genre_facet |
Northwest Territories |
op_source |
Plant Ecology and Evolution 143(3): 340-351 |
op_relation |
info:eu-repo/semantics/altIdentifier/eissn/2032-3921 info:eu-repo/semantics/altIdentifier/pissn/2032-3913 |
op_rights |
info:eu-repo/semantics/openAccess All Rights Reserved |
op_doi |
https://doi.org/10.5091/plecevo.2010.419 |
container_title |
Plant Ecology and Evolution |
container_volume |
143 |
container_issue |
3 |
container_start_page |
340 |
op_container_end_page |
351 |
_version_ |
1810467185766694912 |