Barclay, Richard , McElwain, Jennifer , Dilcher, David , Sageman, Bradley .
Plant cuticle as a tool for taxonomic and paleoenvironmental determination.
Fossil plant cuticle preserves morphological characters useful for answering a variety of ecological and taxonomic questions. Paleobotanical applications involving cuticle have focused on taxonomic identification of species and on reconstructing paleoenvironmental conditions. Taxonomic identification of plants using cuticle characters has long been an endeavor of paleobotanists beginning with Brodie in 1842, and continues to have practical utility today. However, the level of confidence of workers using fossil cuticle has varied extensively. The most conservative approach is to assign fossil specimens to morphotypes, while others with more complete datasets established new species in fossil genera, usually within modern families. One of the key difficulties preventing more extensive use of cuticular traits in plant taxonomic studies is that many of the traits are ecophenotypic. Modern studies have improved our understanding of the relationships between the morphologic and anatomical response of the leaf surface to changes in the abiotic environment. These have improved the accuracy of paleoenvironmental reconstructions based on fossil cuticle and in turn highlight the environmentally conservative traits of greatest taxonomic value, such as stomatal complex type, secretory structures, epidermal striations, trichome type, and trichome location. Environmentally ‘plastic’ leaf surface traits which are recorded in fossil leaf cuticle include stomatal frequency, which is now used as a proxy for paleoatmospheric CO2, and the degree of cell-wall crenulation and the presence of pappillae, both used to identify canopy position. Other morphological features are the result of an interplay between the genotype and phenotypic expression, such as trichome density and stomatal distribution on the leaf. This presentation will review fossil leaf cuticular traits which are of greatest taxonomic utility versus those with the greatest application for paleoenvironmental study using illustrations from an Internet-accessible database, called CUTICLE, recently developed using vouchered herbarium specimens, housed at the Florida Museum of Natural History. (http://fm1.fieldmuseum.org/cuticle/PaleoCollaborator/index.php).
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1 - Northwestern University, Earth and Planetary Sciences, 1850 Campus Drive, Evanston, Illinois, 60208, USA
2 - University College Dublin, School of Biology and Environmental Science, UCD Science Centre West, University College Dublin, Belfield, Dublin, Co. Dublin, D4, Ireland
3 - Florida Museum of Natural History, Dickinson Hall, P.O. Box 117800, Gainesville, Florida, 32611, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM