Celebration of Scholarship and Creative Activity 2021
Ursus americanus, also known as the American black bear, has roamed North America ever since the middle of the Pleistocene Epoch 1.6 million years ago. This makes them an ideal candidate for studying changes in growth over time through comparing fossilized specimens to those of the modern day. When studying the skull sutures of ten modern specimens collected in Wisconsin and analyzed using PAUP V. 4.0, a cladistics software, five growth stages have been able to be determined through adulthood, and with it basal length has been shown to be complementary to being a proxy for growth with maximum length being achieved by stage 2 at 26cm. When using this information, a fossilized Pleistocene skull from Texas was compared to the modern skulls and was determined to be 10% larger than those that shared the same growth stage in this study, reaching 29.3cm in basal length while being between growth stages 2 and 3. To further build upon this study, sexual dimorphisms’ impact on U. americanus skulls may be necessary to understand changes made in adulthood to a skull’s sutures or other characteristics.