2003 Seattle Annual Meeting (November 25, 2003)
Paper No. 236-5
Presentation Time: 2:45 PM-3:00 PM

LATE PALEOCENE PLANTS FROM NORTH DAKOTA: NEW LOCALITIES AND INSIGHTS FROM THE ALMONT FLORA

DEVORE, Melanie L., Department of Biological & Environmental Sciences, Georgia College & State Univ, 135 Herty Hall, Milledgeville, GA 31061, mdevore@mail.gcsu.edu, PIGG, Kathleen B., SOLS Admin & Faculty, Arizona State Univ, PO Box 874501, Tempe, AZ 85287-4501, and MANCHESTER, Steven R., Florida Museum of Natural History, Univ of Florida, Dickinson Hall, PO 117800, Gainesville, FL 32611-7800

The Almont Flora of central North Dakota and equivalent Beicegal Creek floras in western North Dakota are among the best preserved and most diverse (50 genera in 20 families) assemblages of Late Paleocene fossil plants in the world. Fossils are preserved in siliceous shales that reveal both internal structure of fruits and seeds and outer surface features of plant organs. Fossil plants from the original Almont site, known for the past two decades, were recovered from subsurface deposits, making determination of stratigraphic relationships difficult. Investigations of additional sites from the Beicegal Creek area, including one outcrop with the siliceous shale in place, now enable correlation with other units and suggest a Tiffanian (Ti3-Ti5) age based on correlations with published freshwater molluscan and fossil mammals-bearing sites. Based on anatomy, these floras are significant for documenting the oldest reliable occurrences of Cornus (dogwood) and probably Acer (maple) in the fossil record. Mid-high latitude Northern Hemisphere Paleocene floras have typically been characterized as temperate, deciduous and relatively uniform in composition, dominated by such floristic elements as Ginkgo, taxodiaceous conifers, Betulaceae, Platanaceae, Trochodendraceae and Junglandaceae. The Almont and Beicegal Creek floras contain these elements but also document the early occurrences of families that are poorly known in the Paleocene but important in later Tertiary times (Actinidiaceae, Myrtaceae). Among these are the mostly herbaceous family Ranunculaceae which is rarely present in the fossil record prior to the late Neogene. Tropical taxa (Icacinaceae, Menispermaceae, Meliosmaceae) are also represented in these floras. The Almont and Beicegal Creek floras provide a snapshot of a pivotal moment of geologic time as the plants occurring well after the K/T boundary events and preceeding the dramatic changes of the Paleocene-Eocene thermal maximum.

2003 Seattle Annual Meeting (November 25, 2003)
Session No. 236
Paleontology/Paleobotany VI: Paleobotany: Systematics, Ecophysiology, and Paleoclimate
Washington State Convention and Trade Center: 4C-3
1:30 PM-5:30 PM, Wednesday, November 5, 2003

Geological Society of America Abstracts with Programs, Vol. 35, No. 6, September 2003, p. 588

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