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Paleontology, paleoclimatology and paleoecology of the late middle Miocene Musselshell Creek flora, Clearwater County, Idaho; a preliminary study of a new fossil flora

Nina L. Baghai and Robert B. Jorstad
Paleontology, paleoclimatology and paleoecology of the late middle Miocene Musselshell Creek flora, Clearwater County, Idaho; a preliminary study of a new fossil flora
Palaios (October 1995) 10 (5): 424-436

Abstract

The Musselshell Creek flora (12.0-10.5 Ma) of northern Idaho is used to reconstruct paleoclimatic and paleoecologic parameters of the Pacific Northwest during the late Middle Miocene. Other megafossil and microfossil floral records spanning 12.0-6.4 Ma are unknown from this region. The Musselshell Creek fossil flora, previously undescribed, is preserved in lacustrine clays and sediments that accumulated in a narrow valley surrounded by rugged terrain. Dominant taxa include dicotyledons and conifers. Most of the leaves are preserved as impressions or compressions. Some fossil leaves retained their original pigmentation, cellular anatomy, and organic constituents. Other fossils include excellent remains of pollen and spores, dispersed leaf cuticle, pyritized wood, and disarticulated fish bones. A destructive statistical analysis of one block of sediment, approximately 30 cm X 45 cm (1.5 sq. ft) recovered 14 orders, 23 families, and 34 genera of spermatophyte plant fossils. These floral elements are compared with two other earlier Miocene floras which were similarly sampled. Common megafossil genera include Quercus, Zizyphoides, Taxodium, Alnus, Castanea, Magnolia, Acer, Exbucklandia, Sequoia, Populus, and Betula. The rare occurrence of Ginkgo leaves is a first record of this taxon in the Idaho Miocene. Additional plant taxa are represented by palynomorphs. Common pollen taxa are Pinus, Abies, Carya, Quercus, and Tilia. Most of the megafossil and microfossil flora assemblage is characteristic of a streambank to floodplain environment that existed in a warm to cool temperate climate similar to the modern Mid-Atlantic coast of the United States.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 10
Serial Issue: 5
Title: Paleontology, paleoclimatology and paleoecology of the late middle Miocene Musselshell Creek flora, Clearwater County, Idaho; a preliminary study of a new fossil flora
Affiliation: University of Texas at Austin, Department of Botany, Austin, TX, United States
Pages: 424-436
Published: 199510
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 47
Accession Number: 1999-015227
Categories: Paleobotany
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, geol. sketch map
N46°16'00" - N46°53'60", W116°25'60" - W114°37'00"
Secondary Affiliation: Eastern Illinois University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 199906
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