New Insights into Skeletal Morphology of the Oldest Known Silicoflagellates : <i>Variramus</i>, <i>Cornua</i> and <i>Gleserocha</i> gen. nov. = Nouvelles connaissances sur la morphologie du squelette des plus anciennes silicoflagellés connus : <i>Variramu

نویسندگان

  • Kevin McCartney
  • Jakub Witkowski
  • David M. Harwood
چکیده

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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تاریخ انتشار 2015