An adult Pacific mastodon molar believed to be about 10,000 years old has been identified after a field survey in San Mateo County. Pleasanton is about 29 miles north of Saratoga.
Brigid Lynch, a geomorphologist with Balance Hydrologics, spotted the fossil while researching the threatened California red-legged frog for the Midpeninsula Open Space Preserve. An image search indicated the unusual rock could be a mastodon tooth, and paleontologist Wayne Thompson of Pacific Paleontology later confirmed it.
The fossil’s precise location has not been released, but Midpen said it came from redwood forests in the Santa Cruz Mountains section of San Mateo County.
Thompson, a paleontologist for 50 years, said the molar is unusually well preserved. Mastodon teeth often break apart, so the specimen’s condition suggests the animal’s skull could be nearby. Mastodons vanished about 11,700 years ago and once lived across areas including California, Oregon, the northern Rocky Mountain region and parts of Mexico.
Thompson said Ice Age fossils are being exposed more often, including at construction sites covered by environmental protections.