Black Bears (Ursus americanus) versus Brown Bears (U. arctos): Combining Morphometrics and Niche Modeling to Differentiate Species and Predict Distributions Through Time

• Main Author: Kantelis, Theron Michael
• Format: Text
• Language: English
• Published: Digital Commons @ East Tennessee State University 2017
• Subjects: Ursus arctos; Ursus americanus; Bears; Geometric Morphometrics; Ecological Niche Model; Teeth; Molars; Other Environmental Sciences; Paleobiology; Paleontology
• Online Access: https://dc.etsu.edu/etd/3262; https://dc.etsu.edu/context/etd/article/4665/viewcontent/KantelisT050317f.pdf

Late Pleistocene American black bears (Ursus americanus) often overlap in size with Pleistocene brown bears (U. arctos), occasionally making them difficult to diagnose. Large U. americanus have previously been distinguished from U. arctos by the length of the upper second molar (M2). However, the teeth of fossil U. americanus sometimes overlap size with U. arctos. As such, there is need for a more accurate tool to distinguish the two species. Here, 2D geometric morphometrics is applied to the occlusal surface of the M2 to further assess the utility of this tooth for distinguishing U. americanus and U. arctos specimens. When combined with an Ecological Niche Model of U. americanus and U. arctos in North America from the Last Glacial Maximum, this morphometric technique can be applied to key regions. A case of two Pleistocene specimens previously identified as U. arctos from eastern North America exemplifies the utility of this combination.