Paleobiology Commons^™

Exploring The Relationships Between Mammalian Functional Trait Distributions And Regional Biomes, With Application To Miocene Paleoecology, Devra Hock-Reid

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Paleoecology relies on understanding relationships between modern animals and their environment. Animals are adapted to niches in their environments, and those physical adaptations, or functional traits, are utilized as proxies to interpret aspects of paleo-ecosystems. Much is known about individual functional traits in extant mammals and their relationship to the environment. Less is known about how multiple functional traits across a community can be utilized for paleoecological interpretations. I develop models utilizing traits in mammalian communities at the biome level. For Chapter 1, I build a model for North American regional biomes using mammalian trait frequencies. I quantify changes in …

Diatom-Inferred Records Of Paleolimnological Variability And Continental Hydrothermal Activity In Yellowstone National Park, Usa, Sabrina Brown

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Fossil diatoms were used to reconstruct paleoclimatic and hydrothermal conditions in Yellowstone National Park. First, an extensive literature review summarizes the current state of knowledge about eukaryotic organisms characteristic of continental hydrothermal environments. Eukaryotes in hydrothermal systems can live at extremes of acidity (pH 9.0), and at moderately high temperatures (<62 >^○C). Silicate and carbonate precipitation in continental hydrothermal environments is mediated by eukaryotic organisms, which are important members of biofilm communities.

A case study of alkaline-chloride sinter deposits in Yellowstone Lake and the Upper Geyser Basin inferred in-situ diatom growth rather than post-depositional accumulation of valves settling from …

Reconstructing The Paleoecology And Biogeography Of Rhinoceroses (Mammalia: Rhinocerotidae) In The Great Plains Of North America, Leading Up To Their Extinction In The Early Pliocene, Bian Wang

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Members of the family Rhinocerotidae first appeared in the middle Eocene and were one of most successful mammal groups of the Oligocene and Miocene in North America. Their extinction in the early Pliocene has been attributed to several causes, including cooling climate, an expansion of C₄ grasslands, and faunal turnover favoring high-crowned, open habitat-adapted mammalian taxa. This study tests whether the extinction of North American rhinoceroses in the Great Plains was abrupt or gradual by examining changes in their paleogeographic distribution in a series of time-slices through the Barstovian, Clarendonian, and Hemphillian North American land-mammal ages. It further examines …

Ecology And Morphology Of The Late Miocene Musk Deer, Longirostromeryx Wellsi (Artiodactyla: Moschidae: Blastomerycinae), Katheryn Y. C. Chen

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Longirostromeryx wellsi, one of the latest surviving members of the extinct clade Blastomerycinae (Artiodactyla: Moschidae), possesses highly derived craniodental morphology that deviates from typical musk deer form. Previous work suggests that the unique anatomy of L. wellsi represents adaptations for occupying open savannas. To test this hypothesis I conduct principal components analysis on five postcranial bones of L. wellsi, comparing them to that of several extant ruminant artiodactyls, which are divided among seven habitat categories. These elements are also compared with the postcrania of other blastomerycines. These analyses indicate that L. wellsi anatomy is most similar to that of other …

Paleoecology Of Nebraska’S Ungulates During The Eocene-Oligocene Climate Transition, Grant S. Boardman

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The White River Group (WRG) preserves the Eocene-Oligocene climate transition (EOCT), an interval of global cooling and drying during the onset of Antarctic glaciation. In the Great Plains, a shift from forested conditions to drier woodland-savanna biomes is hypothesized to have occurred at this time. I test this hypothesis through the analyses of several paleoenvironmental proxies on the teeth of 12 WRG ungulate species: stable carbon and oxygen isotopes from tooth enamel, and mesowear and microwear texture. The EOCT shift toward more open habitats and lower vegetation density under drying climates should have resulted in an increase in mean carbon …