A stable isotope comparison of the biogenic carbonate of mammalian tooth enamel from the modern Ohio River Valley and Fort Ancient Buffalo sites

Author

• Sara Elizabeth SlackFollow

Date of Award

2026

Degree Name

Biological Sciences

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Dr. Herman Mays

Second Advisor

Ms. Kimberly Dingess

Third Advisor

Dr. Marion Coe

Abstract

δ¹⁸O and δ¹³C values change in response to anthropogenic factors (Ghosh & Brand, 2003). Little is known about the effects of anthropogenic climate and land use change on the ecology of the Ohio River Valley. The goal of this research was to quantify the effects of European colonization on the native ecology of the region. The specific questions of this research were: (1) How have mammalian tooth enamel δ¹⁸O and δ¹³C compositions shifted over time within the Ohio River Valley in response to anthropogenic climate change and vegetation? (2) Are there differences in tooth enamel δ¹⁸O and δ¹³C compositions among species? If so, what species are most impacted by climate change and what is the role of species-specific life histories? (3) Are there differences in δ¹⁸O and δ¹³C compositions between sexes, and if so, how do these differences reflect foraging preferences and behavioral differences between the sexes?

We hypothesized that tooth enamel δ¹⁸O values would increase over time with temperature, while δ¹³C values would fluctuate in response to differences in plant ecology due to forest disruption (Fry, 2006; Hedges et al., 2004; Peterson & Fry, 1987; Tykot, 2004). A total of 89 faunal samples consisting of biogenic carbonate taken from the 3rd molar of mature individuals were analyzed on an Isoprime 100 isotope-ratio mass spectrometer (IRMS) coupled to a MultiFlow-Geo headspace sampler. 30 of these samples originated from the 17^th century Buffalo site (46PU31) and were housed in the Carnegie Museum of Natural History, 55 samples originated from the 20^th century across various West Virginia and Ohio counties and were housed in the Marshall University Biology Department’s museum, and four specimens originated from the 2ist century and were collected from the Southern Ohio Wolf Dog Sanctuary. Five species were sampled: American Black Bear (Ursus americanus), North American Beaver (Castor canadensis), White-tailed Deer (Odocoileus virginianus), Virginia Opossum (Didelphis virginiana), and Eastern Gray Squirrel (Sciurus carolinensis). These samples dated from ~1650 to 2024 AD and due to the non-continuous nature of the data, were initially separated into four bins for analysis 1650, 1940 – 1969, 1970 - 2000, and 2024. A fifth bin, 1940-2000, was used when sample size was unsuitable to separate the 20^th century data into two bins. Three standards were analyzed repeatedly to verify the accuracy of the ratios throughout the runs. Variables included in the analysis were δ¹⁸O, δ¹³C, species, sex, county, ecoregion, bin, and year. Spectrometry data was collected in December 2024 and May 2025. A few samples from December 2024 were rerun in May 2025 to confirm repeatability. A series of ANOVA’s were run and model selection using AICc was used to determine the top model for δ¹⁸O and δ¹³C composition over time. The Suess Effect was accounted for through a spline curve correction of the carbon data. Year, sex, species, and the interaction effect between species and year were considered significant predictors of δ¹⁸O values, while bin, species, and δ¹⁸O variables were considered significant predictors of δ¹³C values. Deer and squirrels had significantly increased δ¹⁸O over time. Squirrel had significantly increased δ¹³C over time, while opossum had significantly decreased. Squirrel had significantly different δ¹⁸O results based on sex, with females having lower values. The data showed that the δ¹⁸O values in squirrels were significantly higher than other species, while δ¹³C values were significantly lower. Beavers were found to have significantly lower δ¹⁸O values than other species. These results show that climate shifts and ecological changes in vegetation may impact certain native species or sexes more significantly than others. This study also highlights the unique compositional nature and potential benefits and constraints to using isotopes from squirrels as a proxy for climate and ecological change.

Subject(s)

Ecology.

Geochemistry.

Archaeology.

Climatic changes.

Land use.

Mammals.

Dental enamel.

Stable isotopes.

Ohio River Valley.

Recommended Citation

Slack, Sara Elizabeth, "A stable isotope comparison of the biogenic carbonate of mammalian tooth enamel from the modern Ohio River Valley and Fort Ancient Buffalo sites" (2026). Theses, Dissertations and Capstones. 2044.
https://mds.marshall.edu/etd/2044