New insights into skeletal morphology of the oldest known silicoflagellates: Variramus, Cornua and Gleserocha gen. nov. |
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| Authors: | Kevin McCartney Jakub Witkowski David M Harwood |
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| Institution: | 1. Department of Environmental Studies, University of Maine at Presque Isle, 181 Main Street, Presque Isle, ME 04769 USA;2. Geology and Palaeogeography Unit, Faculty of Geosciences, University of Szczecin, ul. Mickiewicza 18, 70-383 Szczecin, Poland;3. Department of Earth and Atmospheric Sciences, University of Nebraska–Lincoln, Lincoln, NE 68588-0340 USA |
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| Abstract: | Two of the oldest known silicoflagellate-bearing sediments, lower Albian at Ocean Drilling Program Site 693 in the Weddell Sea of Antarctica and Santonian in the Devon Island sequence of the Canadian Archipelago, are re-examined with a focus on silicoflagellate genera Variramus, Cornua, and Gleserocha that lack basal rings, a feature appearing during late Santonian/early Campanian time within the genus Corbisema. The extraordinary variability of Variramus aculeifera is studied, and a new genus Gleserocha is proposed for taxa with apical structures made of three struts, but without pikes. This new genus includes previously described Variramus wisei and Cornua tapiae and new species G. harrisonii, and is here proposed as a genus transitional between Variramus and Cornua. Two unusual new species of Cornua, C. deflandrei and C. witkowskiana, are also described and a revised terminology is proposed for the skeletal components of Cornua and closely related genera. |
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| Keywords: | Fossil silicoflagellates Cretaceous Antarctic ODP Site 693 Arctic Devon Island |
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