Schreger Angle Analysis of the Kirkland/Lakeview Elementary School Tusk: Mammoth or Mastodon?

Bax R. Barton (1) and Paul R. Kester (2)

(1) Quaternary Research Center, University of Washington, Box 351360, Seattle, WA 98195, USA; baxbarton@collegeclub.com

(2) Geology and Paleontology Division, Burke Museum of Natural History and Culture, Box 353010, University of Washington, Seattle, WA 98195, USA; pkester@u.washington.edu

Recent methodological advances by researchers at the National Fish and Wildlife Forensics Laboratory and the University of Michigan reveal that tusks of mammoth and mastodon may be identified to the generic level based on the analysis of internal Schreger angles. Analysis of an isolated tusk, recovered from lacustrine clayey silt of the Olympia nonglacial interval at Lakeview Elementary School, Kirkland, Washington, revealed 74 measurable Schreger angles that ranged from 43° to 94° (mean = 68°). These values fall well within the previously reported range for Mammuthus sp., and suggest that the Kirkland/Lakeview tusk is from a mammoth (Mammuthus cf. columbi) and not from a mastodon, as previously reported in the press. Secondary data related to this tusk also support this diagnosis. The tusk dates to 16,540 ± 80 14C yr B.P. [CAMS-70709] (19,710 cal yr B.P.). Based on this analysis, the Kirkland/Lakeview mammoth tusk is the youngest dated evidence for mammoths from the Georgia-Puget lowlands.

Schreger Angle Analysis

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