Date of Graduation

12-2022

Document Type

Thesis

Degree Name

Bachelor of Science in Anthropology

Degree Level

Undergraduate

Department

Anthropology

Advisor/Mentor

Terhune, Claire

Committee Member/Reader

Plavcan, J. Michael

Committee Member/Second Reader

Chapman, Kate

Committee Member/Third Reader

Marren, Susan

Abstract

Decreased olfaction, or smell, is a diagnostic characteristic of primates. Despite this, olfaction remains important for diet and social behaviors in primates. To assess how morphological changes impact olfactory-based behaviors between the two major clades of primates, Strepsirrhini and Haplorrhini, this study examined the surface area of the cribriform plate, the bony interface between the brain and nasal cavity. Previous work has found several functional associations between cribriform plate morphology and species diet/ ecology, making this structure possibly more reflective of a species reliance on olfaction in its environment. Primate social structure, such as average group size, mating system, and scent-marking behaviors, and activity patterns also have functional implications for cribriform plate morphology.

Data were comprised of micro computed tomography (microCT) scans collected from MorphoSource.org and the Terhune Lab to measure cribriform plate surface area. The sample represents a wide cross-section of primates and included corresponding data on diet, social system, and activity pattern. Descriptive statistics and t-tests were used to analyze cribriform plate surface area across sex and species. To study in-group and between group variances, phylogenetic generalized least squares (PGLS) and phylogenetic analysis of variance (ANOVA) were performed. From the paired t-tests, no sex difference was found between males and females throughout the sample. Additionally, the phylogenetic regressions showed significant correlations between both plate surface area and margin surface area, as well as between cranial length and plate/margin surface area. From the phylogenetic ANOVAs, no results were significant except the influence of clade (or the evolutionary relationships among species). This novel study reveals that primate olfaction is mainly influenced by clade rather than other factors such as diet, social system, or activity pattern.

Keywords

Cribriform plate; Primate; Clade; Phylogeny; Morphology; Anthropology

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