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Abstract Detail


Tiffney, Bruce [1], Manchester, Steven [2].

A late Paleocene fruit and seed flora from the Fort Union Formation, Sand Draw, Wyoming, investigated by reflected light and x-ray tomography.

The flora of the Paleocene Fort Union Formation in the Rocky Mountain and Great Plains region is best known from fossil leaves and pollen, but fruits and seeds are also available, and provide additional insights into floral composition and potential plant-animal interactions.  A highly fossiliferous lens of ironstone discovered near Sand Draw, Wyoming, by William Keefer in the 1950s contained a carpological flora that was briefly summarized by Jack Wolfe and further explored, but not published, by Richard Scott. Field work in the 1990s augmented this collection, revealing a relatively diverse flora of fruits, seeds, coupled with  poorly preserved leaf impressions.  Many of the fruits and seeds are preserved as molds, rendering visualization and identification difficult because the surface details of the disseminule remain buried in the sediment, and/or hidden beneath a layer of opaque, coalified material, and thus difficult or impossible to view with the dissecting microscope.  While some specimens are beautifully exposed in fortuitous fractures achieved with the blow of a hammer, others are best visualized by the use of micro-CT-scanning and  tomographic reconstruction. Based on these techniques we recognize Diploporus (Taxaceae), Annonaspermum (Annonaceae), Cranea (Betulaceae), Davidia, Mastixia and Langtonia (Cornaceae), an ericalean capsular fruit, Hamamelidaceae,  Iodes and Palaeophytocrene (Icacinaceae), Cyclocarya (Juglandaceae), Magnolia (Magnoliaceae) cf. Sinomenium and possibly a Tinospora-like taxon (Menispermaceae), Platanus (Platanaceae), Meliosma (Sabiaceae), Symplocos? (Symplocaceae), Concavistylon (Trochodendraceae) and Ampelocissus (Vitaceae).  Additionally, foliage of Fagopsiphyllum is present.  Several of these may represent the first clear occurrence of these classic boreotropical taxa in North America. Five of these taxa are putative lianes, which, coupled with the presence of clear trees, suggests a forest of some complexity and density. While some taxa are wind dispersed, others are clearly animal dispersed, marking the growing diversification of birds and mammals and their coevolutionary interactions with the newly evolving clades in the Cenozoic.

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1 - University of California, Santa Barbara, Department of Earth Science and College of Creative Studies, Earth Science MC 9630, University of California, Santa Barbara, California, 93106, United States
2 - Florida Museum of Natural History, University of Florida, Dickinson Hall, 1659 Museum Rd, Gainesville, FL, 32611-7800, United States

fruits and seeds.

Presentation Type: Oral Paper
Session: PAL4, Paleobotany IV: Paleogene Paleobotany
Location: Tucson C/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 3:45 PM
Number: PAL4001
Abstract ID:767
Candidate for Awards:None

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