10,000-Year-Old Mastodon Tooth Discovered in San Mateo County, California

A 10,000‑year‑old molar belonging to an ancient Pacific mastodon was uncovered this month in a San Mateo County preserve on the San Francisco Bay Area’s western edge. Geomorphologist Brigid Lynch, who was conducting routine fieldwork at the site, identified the fossil after noticing an unusual rock formation. Subsequent analysis confirmed the specimen as a well‑preserved mastodon tooth, described by researchers as being in “immaculate condition,” a rarity for remains of the extinct megafauna that once roamed North America.

The discovery adds a valuable data point to the sparse record of mastodon populations in the Pacific coastal region, where few fossils have been recovered. The tooth’s exceptional preservation offers scientists an opportunity to examine the animal’s diet, health and environmental context through isotopic and microscopic studies. Researchers plan to catalog the find within regional paleontological collections and to use it in broader investigations of climate and ecosystem changes at the end of the Pleistocene.