A First Account of Organelle Preservation in Eocene Nonmarine Diatoms: Observations and Paleobiological Implications

Post-eruptive lacustrine sediments that infill a Middle Eocene kimberlitic diatreme near Lac de Gras (Northwest Territories, Canada) have spectacular preservation of diatom microfossils. A single undiagnosed species belonging to the genus Aulacoseira is abundant in this material and reveals, in addi...

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Bibliographic Details
Published in:Palaios 2006-06, Vol.21 (3), p.298-304
Main Authors: WOLFE, ALEXANDER P, EDLUND, MARK B, SWEET, ARTHUR R, CREIGHTON, STEVEN D
Format: Article
Language:English
Subjects:
Algae
anatomy
Aulacoseira
Bacillariophyceae
biologic evolution
Canada
Cell walls
Cenozoic
depositional environment
Diatoms
Eocene
Fossils
Giraffe Pipe
Giraffes
Lac de Gras
lacustrine environment
microfossils
middle Eocene
Northwest Territories
Observational research
Paleobotany
Paleogene
Peridotite
Plantae
preservation
Pyrites
Research Letter
RESEARCH LETTERS
Sediments
SEM data
Taxa
TEM data
Tertiary
Western Canada
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Summary:Post-eruptive lacustrine sediments that infill a Middle Eocene kimberlitic diatreme near Lac de Gras (Northwest Territories, Canada) have spectacular preservation of diatom microfossils. A single undiagnosed species belonging to the genus Aulacoseira is abundant in this material and reveals, in addition to the full complement of siliceous structures comprising the frustule, an array of soft parts that hitherto have been unavailable for study in diatoms of this age. These features include the velar complex, which lines the interior of valves, layered internal membranes, lamellate plastid fragments with pyrenoid-like inclusions, and extracellular mucilagenous bodies. Both ultrastructural and cytoplasmic characters have pronounced affinities with extant congeneric taxa, with an especially close resemblance to the resting cells observed in living Aulacoseira. These observations suggest that modern cellular organization and associated ecological adaptations were present early in the history of nonmarine aulacoseiroid diatoms, implying that prolonged evolutionary stasis has characterized the ecologically important genus Aulacoseira.
ISSN:0883-1351
1938-5323
DOI:10.2110/palo.2005.p05-14e