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Abstract Detail

Themes of land plant evolution, a celebration of the contributions of Leo J. Hickey

Johnson, Kirk [1].

The Vast Potential of the Paleocene Megaflora of the Western Interior of North America.

The most extensive exposures of Paleocene terrestrial strata in the world are present in the Laramide basins of New Mexico, Colorado, Utah, Wyoming, Montana, North Dakota, and South Dakota, and in Saskatchewan and Alberta. Collection of fossil plants in these basins began in the 1860s. Today, the Paleocene megaflora of the Rocky Mountains is an impressive record of over a thousand localities spanning a contiguous region of more than a million square kilometers. It is arguably the largest and most continuous fossil floral sequence of any age. The geographic and temporal density of Paleocene megafloral sites in these rocks provides the opportunity to assess regional vegetation over a ten-million-year period in a range of paleolatitudes, paleoelevations, local sedimentological facies, and position within depositional basins relative to adjacent mountains and seaways. Deposited in a greenhouse world, bracketed by the K-T boundary and the PETM, associated with vertebrate and invertebrate faunas and palynofloras, this record holds tremendous potential for elucidating critical events in Earth history. Leo Hickey, building on a century of work by the USGS, realized this potential and framed the opportunity with a series of significant studies in the Williston, Bighorn and Sverdrup Basins. His students and colleagues have continued this work by: 1) re-collecting old sites with new censusing techniques; 2) enhancing and testing biostratigraphic age estimates with magnetostratigraphy and radiometric dating; 3) using floral morphotyping as a first step toward resolved taxonomy in concert with computer databases that organize high resolution images of both type specimens and multiple examples of morphotypes; 4) describing and naming new species; 5) developing new physiognomic tests and using larger sample sizes, and 6) undertaking comparative studies of modern vegetation to understand the biases imposed by taphonomy and sedimentary facies . Significant challenges exist: 1) many of the historical localities are not precisely located nor their specimens curated; 2) temporal resolution of most sites is relatively poor; 3) taxonomic definition of megafloral elements has not been modernized nor standardized; and 4) foliar physiognomic analysis of paleoclimate is subject to large errors. The potential now exists to resolve 10 million years of Paleocene North American regional phytogeography at a temporal resolution of 100,000 years.

Broader Impacts:

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1 - Smithsonian Institution , National Museum of Natural History, Washington, DC, 20013

Leo Hickey.

Presentation Type: Symposium or Colloquium Presentation
Session: C6
Location: Belle-Chasse/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 3:00 PM
Number: C6006
Abstract ID:951
Candidate for Awards:None

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