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Geology of the Toadstool Park region of northwestern Nebraska, with the lithostratigraphic revision and redescription of the Brule Formation and remarks on Oligocene bone processing

Hannan Earl LaGarry, University of Nebraska - Lincoln

Abstract

Geologic units in the Toadstool Park region of Sioux and Dawes counties, Nebraska, were described and mapped: Holocene and Pleistocene sediments; the Oligocene-Miocene Arikaree Group; the Late Eocene-Oligocene White River Group (Chamberlain Pass, Chadron, and Brule formations); and the Pierre Shale. This mapping indicated that previously used stratigraphic marker beds are areally restricted, hence of limited use. A refined lithostratigraphy was developed to establish new boundaries for the Brule Formation (Orella, Whitney, and "brown siltstone" members), redescribing its members as lithotopes. Rocks of the White River Group are world-renowned for an abundance of fossil bone. The study of concentrated bone residues from the Brule Formation (Orella Member) revealed previously unavailable information about Oligocene paleoecology. Bone processing was identified using autochthonous samples of coprolites and mammalian postcranial bones. Orellan coprolites were produced by a carnivore similar in size and feeding habits to the coyote (Canis latrans), likely the amphicyonid Daphoenus vetus, and five size groups of postcranial bones were moderately processed by several carnivores having canid-like dentitions and "wolf-like" feeding behaviors, likely the canids Hesperocyon and Mesocyon, and the amphicyonids Daphoenus hartshornianus and Daphoenus vetus.

Subject Area

Paleoecology|Geology|Paleontology

Recommended Citation

LaGarry, Hannan Earl, "Geology of the Toadstool Park region of northwestern Nebraska, with the lithostratigraphic revision and redescription of the Brule Formation and remarks on Oligocene bone processing" (1997). ETD collection for University of Nebraska-Lincoln. AAI9815895.
https://digitalcommons.unl.edu/dissertations/AAI9815895

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