ONGOING INVESTIGATIONS INTO THE LATE QUATERNARY DYNAMICS OF PROBOSCIDEANS IN THE UPPER MIDWEST

In the last few decades, mammoth and mastodont localities in the upper Midwest have been central to an emergent understanding of North American megafaunal paleoecology and extinctions. This project explores the state of our knowledge through the documentation of museum collections and the modeling of extant ¹⁴C datasets, capitalizing on previous research to examine the spatio-temporal distribution of proboscidean remains from seven states and provinces. To date, over 300 localities are represented by museum specimens from the study area. Mammut and Mammuthus are distributed throughout the region. Roughly, two thirds of this dataset consists of Mammut americanum, while the remainder is split among Mammuthus jeffersonii and M. primigenius. Mammoth tooth morphology is highly variable throughout this range. Despite the prevalence of proboscidean localities, only 34 of these have direct-dated proboscidean remains, and fewer meet modern criteria of chronological reliability. Because of this, estimates for the extinction of proboscideans in the upper Midwest are highly imprecise: 11.8-9.4 ka (N=17; Mammuthus: 13.7-9.7 ka, N=7; Mammut: 11.9-9.3 ka, N=8). We present preliminary models that indicate these estimates can be greatly refined through the addition of roughly 60 more direct-dated localities. A more refined estimate of the proboscidean extinction window in the upper Midwest will facilitate comparisons to alternate chronologies of cultural and landscape changes (e.g., human colonization, late Wisconsin climate change, etc.).