Differentiating Black Bears (Ursus americanus) and Brown Bears (U. arctos) using Linear Tooth Measurements and Identification of Ursids from Oregon Caves National Monument

• Main Author: Bogner, Emily
• Format: Text
• Language: English
• Published: Digital Commons @ East Tennessee State University 2019
• Subjects: Quaternary; Bears; Bergamn’s Rule; Oregon Caves National Monument; Ursus americanus; Ursus arctos; Evolution; Integrative Biology; Other Ecology and Evolutionary Biology; Population Biology; Orca
• Online Access: https://dc.etsu.edu/etd/3572; https://dc.etsu.edu/context/etd/article/5037/viewcontent/BognerE041819f.pdf

North American black bears and brown bears can be difficult to distinguish in the fossil record due to similar dental and skeletal morphologies. Challenges identifying ursid material from Oregon Caves National Monument (ORCA) called for an accurate tool to distinguish the species. This study utilized a large database of lower tooth lengths and ratios in an attempt to differentiate black and brown bears in North America. Further, this project examined how these linear measurements differ geographically. Analysis of variance (ANOVA) found significant differences between black and brown bears from across North America for every variable studied. Stepwise discriminant analyses (DA) found lengths separated species better than ratios. When sexes were analyzed, ANOVA only found significant differences for lengths while DA found lengths and ratios could not accurately distinguish between sexes. Fossil specimens from North America, including ORCA specimens, demonstrated the utility of this study, supporting several identifications and questioning others.