Antarctic Glossopterids: Clarifying and Comparing Reproductive Structures
Glossopterid reproductive structures, both impressions and permineralizations, have been known from Antarctica for decades, but little detailed work has been done on them to date. Impression fossils from the Central Transantarctic Mountains reveal that at least four genera of reproductive organs are...
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| Other Authors: | , , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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University of Kansas
2009
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1808/6190 http://dissertations.umi.com/ku:10539 |
| Summary: | Glossopterid reproductive structures, both impressions and permineralizations, have been known from Antarctica for decades, but little detailed work has been done on them to date. Impression fossils from the Central Transantarctic Mountains reveal that at least four genera of reproductive organs are present on the continent. Plumsteadia is a genus of multiovulate megasporophylls found on all Gondwanan continents and distinguished by tightly compacted ovules surrounded by a wing which contains a row of ovules at its base. Numerous specimens of Plumsteadia ovata Kyle add additional information on anastomosing venation in the sporophyll and a fluted margin on the wing to the species description. A new species of Rigbya, an ovulate organ, is characterized by the laminar appearance of the cupules/scales and a crenate margin at the apex of the cupules. Eretmonia singulia sp. nov., a microsporangiate structure, is distinguished by the terminal attachment of a single sporangium on a dichotomizing stalk rather than a whorl of sporangia as found in other species. Finally, Arberiella inflectada sp. nov., a cluster of pollen sacs, includes microsporangia with a distinctive, recurved base. These impression genera are found across Gondwana, suggesting that Antarctica, with its central location in the supercontinent, was a bridge for the distribution of glossopterid genera from one Gondwanan continent to another. The relative scarcity of information garnered from these impression specimens presents a conservative estimate of the diversity of the glossopterid clade, but information from Antarctica adds considerably to our knowledge of this group. Permineralized reproductive structures have been known from Antarctica for the past four decades. No formal descriptions have been available for this material, however, leaving a gap in our knowledge of the glossopterid clade. Lakkosia kerasata gen. et sp. nov. is a multiovulate, megasporangiate structure found in silicified peat from the Late Permian Skaar Ridge locality in the ... |
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