Publication Date
8-1-2025
Date of Final Oral Examination (Defense)
4-28-2025
Type of Culminating Activity
Thesis
Degree Title
Master of Arts in Anthropology
Department
Anthropology
Supervisory Committee Chair
Allison Wolfe, Ph.D.
Supervisory Committee Member
Jayson P. Gill, Ph.D.
Supervisory Committee Member
Mark Plew, Ph.D.
Abstract
At the end of the Pleistocene, 38 genera of mammals became extinct in North America, with most of these animals classified as megafauna—terrestrial taxa that weigh 44 kg or more. The cause of these extinctions has often been attributed to either climate change or overkill by humans. Recently, some researchers have implemented a multi-causal framework that incorporates both of these hypotheses, many of which use radiocarbon dates as proxies for abundance to track changes in population levels. Here, I present an alternative methodology using radiocarbon dates to track changes in spatial distribution rather than abundance, with a focus on the four most abundant extinct megafauna genera in the American Southwest (Camelops, Equus, Mammut, and Mammuthus) from the terminal Pleistocene and into the early Holocene. Changes in spatial distribution are examined relative to notable climate change events and the arrival of humans to this region. The results of this study indicate that, overall, all four genera experienced gradual clustering throughout this span. More defined temporal periods within this timeframe show that clustering behavior appears to occur during the cooler conditions associated with the onset of the last Glacial Maximum, and dispersal behavior appears to occur during the warming conditions during the Bølling-Allerød interstadial. This trend does not continue during the cooler conditions of the Younger Dryas. Instead, these genera experience increased dispersal that coincides with the arrival of humans to the American Southwest. Therefore, it seems that climate and then a combination of climate and anthropogenic pressures affected the distribution of these four genera, and potentially led to their extinction. The results of this study demonstrate the utility of using radiocarbon dates as spatial data to predict susceptibility to climate change and humans during the terminal Pleistocene. This methodology can be used to inform contemporary conservation efforts of extant taxa at risk of extinction today.
DOI
https://doi.org/10.18122/td.2423.boisestate
Recommended Citation
Nielsen, Casey T., "Differential Effects of End-Pleistocene Climate Change and Early Humans on Megafaunal Spatial Distribution in the American Southwest" (2025). Boise State University Theses and Dissertations. 2423.
https://doi.org/10.18122/td.2423.boisestate