Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves
Permineralized cycad petioles and/or rachides with associated pinnae are described from two Triassic localities in the Queen Alexandria Range, central Transantarctic Mountains, Antarctica. Petiole‐rachides display an inverted‐omega‐shaped arrangement of vascular bundles typical of most genera of ext...
Published in: | International Journal of Plant Sciences |
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University of Chicago Press
2015
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Online Access: | http://hdl.handle.net/1808/16946 https://doi.org/10.1086/518840 |
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ftunivkansas:oai:kuscholarworks.ku.edu:1808/16946 2023-05-15T13:32:09+02:00 Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves Hermsen, Elizabeth Taylor, Thomas N. Taylor, Edith L. Stevenson, Dennis W. 2015-03-03T20:07:02Z http://hdl.handle.net/1808/16946 https://doi.org/10.1086/518840 unknown University of Chicago Press Hermsen, Elizabeth; Taylor, Thomas N.; Taylor, Edith L.; Stevenson, Dennis W. (2007). "Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves." International Journal of Plant Sciences, 168(7):1099-1112. http://www.dx.doi.org/10.1086/518840 1058-5893 http://hdl.handle.net/1808/16946 doi:10.1086/518840 openAccess Article 2015 ftunivkansas https://doi.org/10.1086/518840 2022-08-26T13:16:28Z Permineralized cycad petioles and/or rachides with associated pinnae are described from two Triassic localities in the Queen Alexandria Range, central Transantarctic Mountains, Antarctica. Petiole‐rachides display an inverted‐omega‐shaped arrangement of vascular bundles typical of most genera of extant Cycadales and exarch primary xylem that link them to the modern order. Pinnae associated with the Antarctic petiole‐rachides are thin, with regularly spaced vascular bundles. They are similar to those of extant Zamia and most other genera of extant Cycadales, whose pinnae lack midribs. Other Mesozoic fossil cycads (e.g., Charmorgia, Lyssoxylon, Lioxylon) have endarch petiole vascular bundles that in some cases were previously considered more similar to those of Bennettitales than those of Cycadales. We suggest, however, that the endarch xylem of these taxa is typical of Cycadales because in extant cycads, the protoxylem changes from endarch to exarch within the base of the petiole. Evolution of cycad leaf form is reviewed based on evidence from the fossil record. Article in Journal/Newspaper Antarc* Antarctic Antarctica The University of Kansas: KU ScholarWorks Antarctic The Antarctic Transantarctic Mountains International Journal of Plant Sciences 168 7 1099 1112 |
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Open Polar |
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The University of Kansas: KU ScholarWorks |
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ftunivkansas |
language |
unknown |
description |
Permineralized cycad petioles and/or rachides with associated pinnae are described from two Triassic localities in the Queen Alexandria Range, central Transantarctic Mountains, Antarctica. Petiole‐rachides display an inverted‐omega‐shaped arrangement of vascular bundles typical of most genera of extant Cycadales and exarch primary xylem that link them to the modern order. Pinnae associated with the Antarctic petiole‐rachides are thin, with regularly spaced vascular bundles. They are similar to those of extant Zamia and most other genera of extant Cycadales, whose pinnae lack midribs. Other Mesozoic fossil cycads (e.g., Charmorgia, Lyssoxylon, Lioxylon) have endarch petiole vascular bundles that in some cases were previously considered more similar to those of Bennettitales than those of Cycadales. We suggest, however, that the endarch xylem of these taxa is typical of Cycadales because in extant cycads, the protoxylem changes from endarch to exarch within the base of the petiole. Evolution of cycad leaf form is reviewed based on evidence from the fossil record. |
format |
Article in Journal/Newspaper |
author |
Hermsen, Elizabeth Taylor, Thomas N. Taylor, Edith L. Stevenson, Dennis W. |
spellingShingle |
Hermsen, Elizabeth Taylor, Thomas N. Taylor, Edith L. Stevenson, Dennis W. Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves |
author_facet |
Hermsen, Elizabeth Taylor, Thomas N. Taylor, Edith L. Stevenson, Dennis W. |
author_sort |
Hermsen, Elizabeth |
title |
Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves |
title_short |
Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves |
title_full |
Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves |
title_fullStr |
Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves |
title_full_unstemmed |
Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves |
title_sort |
cycads from the triassic of antarctica: permineralized cycad leaves |
publisher |
University of Chicago Press |
publishDate |
2015 |
url |
http://hdl.handle.net/1808/16946 https://doi.org/10.1086/518840 |
geographic |
Antarctic The Antarctic Transantarctic Mountains |
geographic_facet |
Antarctic The Antarctic Transantarctic Mountains |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
Hermsen, Elizabeth; Taylor, Thomas N.; Taylor, Edith L.; Stevenson, Dennis W. (2007). "Cycads from the Triassic of Antarctica: Permineralized Cycad Leaves." International Journal of Plant Sciences, 168(7):1099-1112. http://www.dx.doi.org/10.1086/518840 1058-5893 http://hdl.handle.net/1808/16946 doi:10.1086/518840 |
op_rights |
openAccess |
op_doi |
https://doi.org/10.1086/518840 |
container_title |
International Journal of Plant Sciences |
container_volume |
168 |
container_issue |
7 |
container_start_page |
1099 |
op_container_end_page |
1112 |
_version_ |
1766024584811773952 |