Degree Name

MS (Master of Science)

Program

Geosciences

Date of Award

5-2017

Committee Chair or Co-Chairs

Blaine W. Schubert

Committee Members

Steven C. Wallace, Josh X. Samuels

Abstract

Despite being separated by millions of years of evolution, black bears (Ursus americanus) and brown bears (Ursus arctos) can be difficult to distinguish based on skeletal and dental material alone. Complicating matters, some Late Pleistocene U. americanus are significantly larger in size than their modern relatives, obscuring the identification of the two bears. In the past, fossil bears have been identified based on differences in dental morphology or size. This study used geometric morphometrics to look at overall differences in cranial shape and used step-wise discriminant analysis to identify specific characters that distinguish cranial morphology between black and brown bears. Such differences could prove important in identifying fossil bears when crania are present but teeth are missing. Furthermore, being able to properly identify U. arctos and U. americanus crania is important in understanding evolutionary and ecological distinctions among both fossil and modern bears. Principal components, discriminant, and thin plate spline analyses indicated a clear morphological separation between the crania of U. americanus and U. arctos and highlighted key identifying features including a more convex forehead and a narrower, more elongate rostrum in U. arctos than U. americanus.

Document Type

Thesis - Withheld

Copyright

Copyright by the authors.

Available for download on Sunday, October 03, 2021

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