A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants
A new species of late Mid Devonian seed‐megaspore from East Greenland is described and named as Spermasporites allenii . The formerly monotypic genus Spermasporites is emended to accommodate this new species. Rare specimens of S. allenii , with near complete sporangial contents, occur together with...
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crwiley:10.1111/1475-4983.00314 2024-09-15T18:04:14+00:00 A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants Marshall, John E. A. Hemsley, Alan R. 2003 http://dx.doi.org/10.1111/1475-4983.00314 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1475-4983.00314 https://onlinelibrary.wiley.com/doi/pdf/10.1111/1475-4983.00314 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Palaeontology volume 46, issue 4, page 647-670 ISSN 0031-0239 1475-4983 journal-article 2003 crwiley https://doi.org/10.1111/1475-4983.00314 2024-08-01T04:22:35Z A new species of late Mid Devonian seed‐megaspore from East Greenland is described and named as Spermasporites allenii . The formerly monotypic genus Spermasporites is emended to accommodate this new species. Rare specimens of S. allenii , with near complete sporangial contents, occur together with specimens showing proximally adhering microspores. These demonstrate that S. allenii was contained within a sporangium exhibiting extreme anisospory, which is interpreted here as functionally bisexual. This is a key element in understanding its reproductive function. The megaspore was shed along with some attached microspores giving it potential for both cross‐ and self‐fertilization. This confers the advantages of heterospory without recourse to separate micro‐ and megasporangia. This provides a more likely mechanism for seed plant origin than the archaeopteridalean sporangium reduction model. Ultrastructural study of the megaspore wall confirms the progymnosperm affinity of S. allenii . Comparable forms include the Frasnian Spermasporites devonicus and the Famennian seed‐megaspores isolated from Archaeosperma arnoldii . Article in Journal/Newspaper East Greenland Greenland Wiley Online Library Palaeontology 46 4 647 670 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
A new species of late Mid Devonian seed‐megaspore from East Greenland is described and named as Spermasporites allenii . The formerly monotypic genus Spermasporites is emended to accommodate this new species. Rare specimens of S. allenii , with near complete sporangial contents, occur together with specimens showing proximally adhering microspores. These demonstrate that S. allenii was contained within a sporangium exhibiting extreme anisospory, which is interpreted here as functionally bisexual. This is a key element in understanding its reproductive function. The megaspore was shed along with some attached microspores giving it potential for both cross‐ and self‐fertilization. This confers the advantages of heterospory without recourse to separate micro‐ and megasporangia. This provides a more likely mechanism for seed plant origin than the archaeopteridalean sporangium reduction model. Ultrastructural study of the megaspore wall confirms the progymnosperm affinity of S. allenii . Comparable forms include the Frasnian Spermasporites devonicus and the Famennian seed‐megaspores isolated from Archaeosperma arnoldii . |
format |
Article in Journal/Newspaper |
author |
Marshall, John E. A. Hemsley, Alan R. |
spellingShingle |
Marshall, John E. A. Hemsley, Alan R. A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants |
author_facet |
Marshall, John E. A. Hemsley, Alan R. |
author_sort |
Marshall, John E. A. |
title |
A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants |
title_short |
A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants |
title_full |
A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants |
title_fullStr |
A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants |
title_full_unstemmed |
A Mid Devonian seed‐megaspore from East Greenland and the origin of the seed plants |
title_sort |
mid devonian seed‐megaspore from east greenland and the origin of the seed plants |
publisher |
Wiley |
publishDate |
2003 |
url |
http://dx.doi.org/10.1111/1475-4983.00314 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1475-4983.00314 https://onlinelibrary.wiley.com/doi/pdf/10.1111/1475-4983.00314 |
genre |
East Greenland Greenland |
genre_facet |
East Greenland Greenland |
op_source |
Palaeontology volume 46, issue 4, page 647-670 ISSN 0031-0239 1475-4983 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/1475-4983.00314 |
container_title |
Palaeontology |
container_volume |
46 |
container_issue |
4 |
container_start_page |
647 |
op_container_end_page |
670 |
_version_ |
1810441734135480320 |