A tooth from the Ice Age: Mastodon fossil found in San Francisco Bay Area

Published on 21/09/2026 - 7:35 GMT+2

A fossilised tooth of a prehistoric relative of a modern elephant has been found in northern California that scientists say provides a valuable window to the Ice Age. The tooth belonged to a Pacific mastodon that lived in North America.

Geomorphologist Brigid Lynch spotted it while working on a habitat restoration project in a creek in San Mateo County, south of San Francisco. The tooth was partly submerged in the water and stood out from the surrounding rocks.

"It was just sitting there in the middle of the creek, halfway in, half out of water," Lynch said.

At first, however, she and her colleagues were unsure what they had found. The fossil was eventually identified using a reverse image search.

"Very immediately, it popped up with this is a Pacific mastodon molar fossil," Lynch said.

From creek to collection

Researchers say the tooth is in remarkably good condition, with both its crown and root intact.

Chrissy Garcia, curator at Stanford University's Geoscience Specimen Collection, said scientists already knew mastodons and mammoths had lived in the Bay Area during the Pleistocene Epoch. But she expressed surprise over the way this particular fossil had been discovered.

The tooth has been donated to Stanford University, where researchers plan to determine its age and create a 3D copy for public education.

Scientists say the specimen could also provide new opportunities for research as technology develops and new scientific questions emerge.

The discovery also highlights the role of protected open spaces in preserving evidence of the region's distant past.

For thousands of years, the mastodon's tooth lay hidden in a California creek. Now, it is becoming a window into a world that disappeared long before the modern Bay Area took shape.

Video editor • Yolaine De Kerchove Dexaerde