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San Mateo creek yields 10,000-year Pacific mastodon tooth

By Drooid · Sep 12, 2026, 10:42 PM UTC · How we work

Summary

Midpen Discovers Mastodon

Midpeninsula Regional Open Space District discovered an exceptionally preserved Pacific mastodon tooth in a San Mateo County creek.
The molar measures about 8.5 inches long, 7 inches deep, and 3 inches wide.
Scientists estimate the tooth is at least 10,000 years old, dating to the end of the Ice Age.
Midpen donated the specimen to Stanford’s Doerr School of Sustainability for carbon dating, research, and a 3D scan.

Summary

Midpen Stores Tooth

Midpeninsula Regional Open Space District stores the mastodon molar in a Stanford room without chemical preservatives.
The district will not disclose the creek location where the tooth was found.
Spokesman Ryan McCauley likened the discovery to a “Jurassic Park” scene.
Curator Christine Garcia monitors the tooth as it slowly dries instead of displaying it publicly.
The district cites the 2013 Calaveras Reservoir dig, which uncovered megashark teeth and hippo fossils, as comparable.

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Midpen Discovers Mastodon

Midpeninsula Regional Open Space District discovered an exceptionally preserved Pacific mastodon tooth in a San Mateo County creek.
The molar measures about 8.5 inches long, 7 inches deep, and 3 inches wide.
Scientists estimate the tooth is at least 10,000 years old, dating to the end of the Ice Age.
Midpen donated the specimen to Stanford’s Doerr School of Sustainability for carbon dating, research, and a 3D scan.

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