A Geologist in California Found Something Strange Sticking Out of a Creek. A Reverse Image Search Told Her It Was an Ancient Mastodon Tooth

It’s big and multi-faceted, with strange protrusions sticking out of the main body. Brigid Lynch, a geomorphologist at Balance Hydrologics, spotted it in a creek in California’s San Mateo County and thought it could be an animal. The mysterious object in question turned out to be an exceptionally well-preserved ancient mastodon molar and a reminder of the megafauna that once roamed the region.

Lynch and a colleague had been conducting field surveys for a conservation project for California red-legged frogs, a federally threatened species, and Lynch had no idea that she’d found and photographed something so special. Then, however, "she did a reverse Google image search and found out that it might be a molar of an Ice Age mastodon,” Wayne Thompson, a paleontologist and CEO of the fossil mitigation company Pacific Paleontology, tells Sooji Nam for CBS News Bay Area. The Midpeninsula Regional Open Space (Midpen)—an independent district in the greater Santa Cruz Mountains that cares for 70,000 acres of public open space—asked Thompson to confirm the “gigantic” finding.

"I confirmed it was a mastodon tooth. And everybody is pretty excited about it, because these don't show up all that often," Thompson adds. Lynch discovered the intact tooth in one of Midpen’s preserves in San Mateo County.

The fossilized molar belonged to an adult Mammut pacificus, or a Pacific mastodon. Mastodons are now-extinct elephant-like herbivores that were shorter and stockier than mammoths and also had shorter and straighter tusks. Another differing factor has to do with their diets: mammoths fed on grasses, while mastodons were browsers, meaning they ate vegetation or fruits from tall plants.

Pacific mastodons are the most recently recognized mastodon species, and they have narrower teeth, thicker leg bones and different tusks than the more established American mastodon (Mammut americanum). Experts theorize that Pacific mastodons moved across modern-day California, Oregon, the northern Rocky Mountain region of the western United States and parts of Mexico. They lived from 2.5 million years ago to approximately 11,700 years ago, joining a host of other Ice Age megafauna that went extinct around the time.

In what is now California, Pacific mastodons would have existed alongside other bygone species, including Jefferson’s ground sloths, western camels and Columbian mammoths, as well as animals that still exist, like gray foxes, Steller’s jays and spotted owls. 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 says in a Midpen statement.