Well-Preserved Tooth From Pacific Mastodon Found in a Creek in San Francisco Bay Area

A scientist made a surprising discovery while working near a creek in the San Francisco Bay Area — a fossilized tooth from a Pacific mastodon. Brigid Lynch, a scientist who studies how land and water shape each other, spotted the tooth earlier this year. She was not even looking for fossils. She was working on a project to help protect the California red-legged frog, a threatened species that lives in the area.

Lynch said the tooth was easy to spot because it stood out from the rocks around it. 'I keep joking it wasn't hard to find,' she said. 'It was just sitting there in the middle of the creek, halfway in, half out of the water.' The tooth belonged to a Pacific mastodon, a large animal that looked similar to an elephant and lived in North America thousands of years ago.

Lynch was working in a preserve run by the Midpeninsula Regional Open Space District in San Mateo County. The district manages more than 70,000 acres of land in the Santa Cruz Mountains. After the find was announced this week, the fossil was donated to Stanford University's Doerr School of Sustainability, where scientists can study and care for it properly.

Chrissy Garcia, a curator at Stanford who manages the school's collection of natural specimens, said the tooth is in excellent shape. 'So we've got both the crown and the root of the fossil. You can even see root canal,' she said. The tooth measures about 9 inches, or 23 centimeters, long. Garcia said it is exciting to have a fossil of such high quality that was found so close to home.

Pacific mastodons are an extinct species, meaning they no longer exist on Earth. Ron Tykoski, a fossil expert at the Perot Museum of Nature and Science in Dallas, Texas, said several types of mastodons once roamed North America. These animals lived for millions of years before disappearing about 10,000 to 12,000 years ago. Tykoski added that mastodon fossils are found fairly often, depending on where you live.

Tykoski also pointed out that many important fossils are discovered by everyday people in unexpected places. 'The way this was found is actually the way a lot of specimens are found, just somebody who happened to be in the right place,' he said. Lynch's discovery is a good example of how paying attention to your surroundings can lead to something amazing. Scientists are trained to notice things that seem out of place in nature.

Garcia said researchers will likely try to find out exactly how old the tooth is. They also plan to make a detailed 3D copy of it to give back to the open space district. The district says it will use the copy to teach the public about the area's natural history. Having a copy means more people can see and learn from the fossil without risking damage to the real one.

Ryan McCauley, a spokesperson for the district, said the discovery shows why protecting open land matters. He noted that the tooth was found while scientists were trying to save another species from going extinct. 'That this tooth, that this molar, was found in the context of trying to protect the habitat and save another species from potentially going extinct I think really just drives home the point of why it's so important to care for these open spaces and these natural lands,' he said. The find connects the past and the present in a powerful way.