Scientist Finds Mysterious Tooth In SMC Creek With A Prehistoric Surprise

SAN MATEO COUNTY, CA — A scientist conducting field surveys in San Mateo County recently spotted what appeared to be an oddly shaped rock in a creek bed but paleontologists later confirmed it was an intact mastodon tooth, the Midpeninsula Regional Open Space District announced Wednesday.

Brigid Lynch, a geomorphologist with Balance Hydrologics, discovered the tooth while surveying the area as part of a habitat enhancement project supporting California red-legged frogs, a threatened species.

“As a geologist, I've gone out and seen stuff in the field, but definitely nothing as exciting as this,” Lynch said.

Paleontologist Wayne Thompson determined the fossil was an intact molar from an adult Pacific mastodon and described it as being in immaculate condition, according to Midpen.

"It's the most complete mastodon molar from our area, and the most spectacular mastodon molar that I've ever seen. I had chills and shivers up and down my spine,” Thompson said. “It's another puzzle in the Ice Age saga that we can put into place.”

The Pacific mastodon, Mammut pacificus, was formally recognized as a distinct species in 2019, according to the U.S. Geological Survey. Fossils identified as the species have been found throughout California and at two sites in southern Idaho, the U.S. Geological Survey reported.

Researchers believe Pacific mastodons’ originally roamed areas in what is now California, Oregon, the northern Rocky Mountain region of the western United States and parts of Mexico.

“This highlights for me that the presence of mastodons wasn't that long ago, in geologic time,” said Matt Sharp Chaney, a Midpen biologist. “That mastodon were out here in the same landscape that we’re in today really drives home how important the work that we do is to keep species from winking out forever.”

Unlike mammoths, which primarily fed on grasses, mastodons used their trunks to strip leaves, shoots and fruit from vegetation, according to Midpen.

The fossilized tooth was donated to Stanford University’s Doerr School of Sustainability, where researchers plan to use carbon dating to determine its exact age, Midpen reported.

Researchers said they will use carbon dating on the molar to determine its exact age, and they will perform a 3D-scan and print a copy for Midpen to use for public outreach and education.

“Fossils are our only opportunity to see into past biodiversity,” said Christine Garcia, Geoscience Specimen Collection manager at Stanford. “We can study fossils to better understand Earth’s past, past wildlife and the ecosystem they were a part of, and to help us make better predictions and better decisions about how to help our ecosystems and biodiversity thrive into the future.”