Liu, (Christopher) Yusheng , Wright, Taylor , Bassaly, Shady Magdy .
The occurrence of East Asian plants in the Late Miocene-Early Pliocene flora from Gray, northeastern Tennessee.
A new Late Neogene fossil site was recently discovered during highway construction at Gray, a small community in northeastern Tennessee (36.5oN, 82.5oW). The fossil site, now known as the Gray Fossil Site (GFS), is dated as the latest Miocene to earliest Pliocene (4.5-7 million-year olds) according to the stratigraphic range of the recovered rhino Teleoceras and short-faced bear Plionarctos. It represents a unique combination of North American and Eurasian plant and animal taxa in a forest refugium. Among plant materials, abundant fruit/seed remains are well preserved. One of the uniqueness in the flora is the occurrence of numerous taxa with close East Asian affinities or being endemic now to East Asia. Preliminary studies show that fossils with close East Asian affinities probably include Carya (Juglandaceae) endocarps and Vitis (Vitaceae) seeds, while those now endemic to East Asia are Sinomenium (Menispermaceae) endocarps and seeds of Sargentodoxa (Sargentodoxaceae). Endocarps of Sinomenium are rather confused with those of Menispermum, a genus of the same family and the extant species are also present in southeast United States. Characters found to be diagnostic in endocarps include the size, shape and orientation of forman and attachment of ridges developed on keel. Although we now roughly know that the elimination of most of the Asian exotics from the North America flora dates to the Late Miocene to Pliocene as a result of a decline in summer rainfall, the fossils from the GFS could help us understand in more detail how and when those East Asian related plants became extinct in southeast United States. Furthermore, it is also useful in discuss the development of the East Asian and southeastern North American disjunction pattern, shared by about 65 extant seed plant genera.
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Gray Fossil Site
1 - East Tennessee State University, Biological Sciences, PO Box 70703, Johnson City, TN, 37614-1700, USA
2 - East Tennessee State University, Biological Sciences, PO Box 70703, Johnson City, TN, 37614-1700, USA
Gray Fossil flora
Asian/North American disjunctions
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM