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Extinction of Harrington's mountain goat
J I Mead1, P S Martin, R C Euler
1Department of Geology, Northern Arizona University, and Museum of Northern Arizona, Flagstaff, AZ 86011.
Summary
Harrington's mountain goats (Oreamnos harringtoni) lived in the Grand Canyon for over 19,000 years. Their extinction, along with Shasta ground sloths, coincided with the arrival of Clovis hunters.
Area of Science:
- Paleontology
- Quaternary Science
- Archaeology
Background:
- Keratinous horn sheaths of Harrington's mountain goat (Oreamnos harringtoni) were discovered in Grand Canyon caves.
- Previous research suggested sequential extinctions of megafauna during climatic warming events.
Purpose of the Study:
- To determine the extinction timeline of Harrington's mountain goat in the Grand Canyon.
- To compare the extinction timing of Harrington's mountain goat with Shasta ground sloths (Nothrotheriops shastensis).
- To investigate the potential role of human arrival in these extinctions.
Main Methods:
- Non-destructive dating of 23 keratinous horn sheath specimens using tandem accelerator mass spectrometry (TAMS).
- Radiocarbon dating of both Harrington's mountain goat and Shasta ground sloth remains.
- Analysis of extinction patterns in relation to regional climate and human presence.
Main Results:
- Harrington's mountain goat inhabited the Grand Canyon for at least 19,000 years, becoming extinct by 11,160 +/- 125 radiocarbon years before present.
- Extinction dates for Harrington's mountain goat and Shasta ground sloths were not significantly different, indicating concurrent loss.
- Both extinctions align with the regional arrival of Clovis hunters.
Conclusions:
- The extinction of Harrington's mountain goat and Shasta ground sloths in the Grand Canyon occurred concurrently.
- The arrival of Clovis hunters in the region is contemporaneous with these megafaunal extinctions.
- These findings challenge sequential extinction models and suggest a potential link between human presence and megafaunal loss.
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