California: 10,000-year-old mastodon tooth discovered in creek

A Pacific mastodon molar, estimated to be around 10,000 years old, was discovered in the bed of a creek in San Mateo County, California. The nearly intact fossil will now undergo more precise dating at Stanford University.

Brigid Lynch, a geomorphologist at Balance Hydrologics, made the find during a study conducted in a reserve within the Midpeninsula Regional Open Space District. Her team was looking for ways to improve the habitat of the California red-legged frog, a threatened species.

Initially, the object resembled an unusually shaped rock. Paleontologists later identified it as a complete molar that belonged to an adult Pacific mastodon. The tooth measures approximately 21.6 centimeters long, 17.8 centimeters deep, and 7.6 centimeters wide.

Paleontologist Wayne Thompson describes it as the most complete mastodon molar found in this region. Its state of preservation is considered exceptional, although the age of 10,000 years remains an estimate for now.

Carbon dating planned at Stanford

The Pacific mastodon lived in the western part of North America during the Pleistocene. Recognized as a distinct species from the American mastodon in 2019, it was characterized by narrower teeth, thicker leg bones, and a different shape of tusks. The species went extinct about 11,700 years ago.

The Midpeninsula Regional Open Space District has entrusted the molar to the Doerr School of Sustainability at Stanford. Researchers plan to conduct carbon dating, a three-dimensional scan, and create a replica for public awareness.