Strange rock catches scientist's eye during creek search, leading to rare discovery

A scientist surveying a creek in San Mateo County, California, has made an unexpected discovery: a tooth from the mouth of an Ice Age giant. The tooth, which belonged to an ancient Pacific mastodon, was found by Brigid Lynch, a geomorphologist with Balance Hydrologics, in a Midpeninsula Regional Open Space District preserve. Mastodons were massive, elephant-like herbivores that went extinct around 11,700 years ago.

The tooth was discovered in a creek where Lynch was surveying the area as part of an effort to improve the habitat of the threatened California red-legged frog. Lynch initially thought the tooth was an oddly shaped rock, but it has since been confirmed as a molar from a mastodon. The tooth is in "immaculate condition," according to Wayne Thompson, CEO of Pacific Paleontology, who examined the fossil and assessed the site where it was discovered.

Thompson estimates that the tooth likely dates back between 50,000 and 100,000 years, based on where it was found. He notes that the condition of the tooth offers clues about what happened to it after the mastodon died, suggesting that it "hadn't moved very much in the stream where the creature died." Thompson believes that the rest of the animal may still be buried at the site.

The discovery of the tooth is considered rare, as mastodon molars are typically fragile and prone to damage. Thompson notes that it is "extremely rare" to find a mastodon molar in such well-preserved condition. Researchers from Stanford University's Doerr School of Sustainability plan to carbon date the molar to determine its exact age and create a 3-D scan of the tooth to produce a replica.

The creek where the tooth was found is lined with alder trees, which were among the preferred food sources of mastodons. Thompson notes that the discovery provides insight into the habits and habitats of these ancient creatures, and researchers will continue to study the site to learn more about the mastodon's presence in the area.