Master's Theses

Document Type

Thesis - campus only access

Date of Award

Spring 1994

Degree Name

Master of Science (MS)

Department

Geosciences

Advisor

Richard Zawerksi

Abstract

The Beckerdite local biota, Clark County, Kansas, is the first Miocene fossil locality to be described from southwestern Kansas. This study was undertaken to get an overview of this site, because of the lack of Miocene paleontological data from this area, and the site's central location between classic Miocene sites in northwestern Kansas and the panhandles of Texas and Oklahoma. Basic surveying techniques were employed while excavating the site, including: horizontal and vertical control points used in conjunction with a grid system that can be expanded in any direction as needed; and setting of semi-permanent monuments so that the grid system can be easily re-established in any future excavation. The fossils were collected from fluvial sediments of the Ogallala Group. The biota consist of at least 5 plant, 4 invertebrate, and 17 vertebrate taxa, including the first report of a crocodilian from the Miocene of Kansas. Based on the presence of Osteoborus and Megatylopus the biostratigraphic age of the biota is Hemphillian; the presence of Epicyon, Nimravides, and Procamelus indicate an early Hemphillian age. The biota is roughly contemporaneous with these faunas in Kansas: Swayze Quarry, Clark County; Bemis local fauna, Ellis County; Minium Quarry local biota, Graham County; and the Long Island local fauna, Phillips County. In an attempt to understand the depositional environment of the site, a sieve analysis of the sediment was made on one representative sample from the site. The results (mean grain size = 2.26 phi, median grain size = 2.13 phi, skewness = 0.17, and standard deviation 1.19) suggest that this sample was deposited in a fluvial system. Taphonomic evidence would suggest that the vertebrate remains were weathered on the surface before burial, and subsequently reworked and winnowed by the fluvial system. This evidence includes exfoliation cracks, the type of bones recovered, and stream-rounded edges on many of the elements. In contrast, the plants and invertebrate remains do not show extensive transport. The organisms in the Beckerdite local biota indicate that the area around the site of deposition was a savanna parkland with a mosaic of grasslands, trees, and shrubs. Based on the presence of the large reptiles (Geochelone and crocodilian) the climate was temperate, rarely exceeding 38[degrees] C or dropping below 0[degrees] C.

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Rights

© 1994 Gregory A. Liggett

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