North American black bears (U. americanus) and brown bears (U. arctos) 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. Ursid teeth have a high degree of variability and morphological features are not always diagnostic. This study utilized a large database of lower tooth lengths (p4, m1, m2, and m3) and ratios (p4/m1, m2/m1, m3/m1, p4/m3, m2/m3) in an attempt to differentiate U. americanus and U. arctos in North America. Further, this project examined how these linear measurements differ in response to ecoregion, latitude, and climate. Analysis of variance (ANOVA) found significant differences between U. americanus and U. arctos from across North America for every variable studied. Stepwise discriminant analyses (DA) found lengths separated species better than ratios with 99.1% correct classification versus 77.5% correct classification for ratios. When sexes were analyzed, ANOVA only found significant differences for lengths while DA found lengths and ratios could not accurately distinguish between sexes; only 72.1% of sexes were classified correctly while utilizing lengths and 61% for ratios. Seventeen previously identified fossil specimens from across North America, in addition to the ORCA specimen, demonstrated the utility of this study, confirming several identifications and rejecting others, proposing the need for new designations.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:asrf-1418 |
| Date | 12 April 2019 |
| Creators | Bogner, Emily, Schubert, Blaine W, Samuels, Josh X |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | Appalachian Student Research Forum |
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