Abstract Detail

Beringia!: Current Insights on the Geology, Climate, Paleontology, Floristic Assembly, and Biodiversity of a Subcontinent that is Central to Northern Hemisphere Biogeography

Manchester, Steven [1].

Similarities between Paleocene and Eocene floras of eastern Asia and western North America and implications for floristic continuity across Beringia.

Taxonomic comparisons of seed plants in Paleocene and Eocene floras of the Northern Hemisphere provide important clues to the routes of biogeograpic exchange between northern land masses. The plant megafossil remains collected from lake bed deposits of eastern Asia and western North America have been compared with each other and with floras of similar age in Europe in order to infer taxa that probably spread their ranges across Beringia vs those that extended across Greenland and to Europe. Special attention is given to well-collected floras including the Paleocene Wuyun and Altai floras of China, the Amur flora of Russia, the Kuji flora of Japan, and the Fort Union of North America; and early to middle Eocene sites including Fushun, Huadian and Yilan in China and Yubari, Japan, and the Republic, Clarno, and Green River floras of western North America. These were compared also with the Paleocene Mull flora of Scotland and middle Eocene Messel and Eckfeld floras of Germany. Genera shared between Paleocene floras of western North America and eastern Asia, but apparently not Europe, include Acer, Amersinia, Celtis, Cornus, Davidia, Dipteronia, Limnobiophyllum, Porosia, Ulmites, Metasequoia and Ditaxocladus. By the Eocene, additional genera shared between eastern Asia and western North America but not known from Europe include Alnus, Fagus, Platimeliphyllum, and Ulmus. These Paleogene distribution patterns imply range expansion via the Bering land bridge. What these taxa share in in common is mostly temperate, deciduous habit. Other taxa common in the Eocene of western North America, such as diverse Juglandaceae (e.g. Cruciptera, Cyclocarya, Engelhardia, Platycarya, Cruciptera, Engelhardia), Menispermaceae, Sabiaceae, and Vitaceae are shared with European floras but apparently not with eastern Asian Paleocene and Eocene floras, suggesting that these more thermophilic taxa may have traversed the North Atlantic land bridge but were unsuccessful to access the more northerly Beringial corridor. Although some genera were circumboreal by the Paleocene and/or Eocene (e.g. Comptonia, Jenkinsella, Nordenskioeldia, and Palaeocarpinus, floristic similarities between eastern Asian floras and European floras exclusive of North America appear to have been very limited, presumably due to the barrier of the Turgai Seaway. Detailed investigations of the above-mentioned genera, expanding on their fossil records and incorporating them into phylogenetic analyses can help in understanding the timing and directions of range expansion across Beringia.

1 - Florida Museum Of Natural History, Dickinson Hall, Museum Rd & Newell Dr., Gainesville, FL, 32611, United States

none specified

Presentation Type: Symposium Presentation
Number: S1007
Abstract ID:1017
Candidate for Awards:None

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