Degree

Master of Science (MS)

Department

Geology

Document Type

Thesis

Abstract

The Fossil Lake locality in south-central Oregon is rich in many species of fossil remains and is also home to packages of sandstone that grade upward into finer siltstone or claystone. These packages have been interpreted to represent rising and falling lake levels as a result of glacial transgressive and regressive sequences. The fossil vertebrates and invertebrates have also fluctuated because of the different climates at Fossil Lake. Although the stratigraphic distribution of most classes of animals have been determined, fossil birds have not. Here, the distribution of 329 avian fossils is presented in the stratigraphic framework. The species were divided into eco-groups based on their morphological adaptations: terrestrial, shallow-water, and diving birds. From the distribution of each species and eco-group, the lake level was found to gradually fall through the section. The conclusions from the distribution of birds were compared to the distribution of other vertebrates, the distribution of invertebrates, carbon isotopes, and oxygen isotopes. This helped create a more precise understanding of the numerous environmental changes at Fossil Lake through time. Although some units have more identified specimens than others, fossil Aves show the cycling of wet and dry cycles as the lake level gradually falls before heavily rising before the Last Glacial Maximum.

Date

2-6-2026

DOI

https://proquest.com/docview/3347959138

First Committee Chair

Jennifer Hargrave

First Committee Member

James Martin

Second Committee Member

P. Ioannidi

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