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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 1965 was briefly summarized by Jack Wolfe and further exoplored, but not published, by Richard Scott. Field work in the 1990s augmented these collections, revealing a diverse flora of fruits, seeds, coupled with poorly to moderately preserved leaf impressions. Many of the fruits and seeds are preserved as molds, rendering visualization and identification difficult because many of the surface details of the fruit remain buried in the sediment, and/or hidden beneath a layer of opaque, coalified material, and thus difficult or impossible to view at 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 a Cupressaceae cone, Diploporus (Taxaceae), Annonaspermum (Annonaceae), Cranea (Betulaceae), Mastixia and Langtonia (Cornaceae), an Ericalean capsular fruit, Iodes, and Palaeophytocrene (Icacinaceae), Cyclocarya (Juglandaceae), Magnolia (Magnoliaceae) cf. Palaeosinomenium (Menispermaceae), Meliosma (Sabiaceae), Acer? (Sapindaceae), Concavistylon (Trochodendraceae), and cf. Vitis (Vitaceae). Additionally, foliage of Ginkgo and Fagopsiphyllum is present. Several of these may represent the first clear occurrence of these classic boreotropical taxa in North America. Four 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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