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Cytological and Ultrastructural Preservation in Eocene Metasequoia Leaves from the Canadian High Arctic

Karimah Schoenhut, David R. Vann and Ben A. LePage
American Journal of Botany
Vol. 91, No. 6 (Jun., 2004), pp. 816-824
Stable URL: http://www.jstor.org/stable/4122696
Page Count: 9
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Cytological and Ultrastructural Preservation in Eocene Metasequoia Leaves from the Canadian High Arctic
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Abstract

The ultrastructural examination by transmission electron microscopy of 45-million-year-old mummified leaves of Metasequoia extracted from the Upper Coal member of the Buchanan Lake Formation in Napartulik on Axel Heiberg Island revealed the preservation of intact chloroplasts and chloroplast components. Abundant tanniferous cell inclusions may indicate that the 3-mo period of constant daylight during the Artic summer induced high concentrations of tannins in the leaf tissues, which may have arrested microbial degradation of the litter. Quantified differences in the extent of chloroplast preservation through a vertical section of the lignite suggest that short-term shifts in the depositional environment took place, perhaps influencing the exposure of the leaf tissues to conditions that would either promote or inhibit decomposition.

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