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Paleobotanical Section

Manchester, Steven R. [1], Archibald, Bruce [2].

Phytogeographic significance of the Eocene flora of Horsefly, British Columbia.

About thirty genera, including a few ferns, gymnosperms, and many angiosperms, are known based on impressions of leaves, fruits and seeds from Middle Eocene lacustrine shales of Horsefly, British Columbia, Canada. The Horsefly flora shows similarities to early and middle Eocene floras of eastern Asia as well as to early and middle Eocene floras of midcontinental North America. Ginkgo, Metasequoia, Pinus, Koelreuteria, Nyssidium, Ulmus, and Deviacer are shared with the Eocene of Northeastern China. Fagopsis, an extinct genus best known from the late Eocene of Florissant, Colorado, is represented by both fruits and leaves from Horsefly. Macginitiea is seen here at its most northerly occurrence in North America. Dipteronia, Palaeocarpinus, Florissantia, Sassafras, and an extinct fruit type with paired, apically extended wings, are among the taxa shared with other western North American Eocene floras. These comparisons demonstrate probable floristic exchange between northwestern North America and Northeastern China during the early and/or middle Eocene. In contrast, the Horsefly flora shows very little generic similarity to Early and Middle Eocene floras of Europe. Farther to the south, the Clarno Formation of Oregon includes elements shared with European Eocene floras as well as with the Horsefly and Chinese assemblages.

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1 - Florida Museum of Natural History, Dickinson Hall, P.O. Box 117800, Gainesville, Florida, 32611, USA
2 - Harvard University, Organismic and Evolutionary Biology, Museum of Comparative Zoology, Cambridge, Massachusetts, 02138, USA

British Columbia

Presentation Type: Oral Paper
Session: 17-1
Location: 404/Hilton
Date: Monday, August 15th, 2005
Time: 1:30 PM
Abstract ID:474

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