{"id":8907,"date":"2026-09-11T07:37:16","date_gmt":"2026-09-11T07:37:16","guid":{"rendered":"https:\/\/nextcitydigest.com\/?p=8907"},"modified":"2026-09-11T07:37:16","modified_gmt":"2026-09-11T07:37:16","slug":"immaculate-condition-rare-mastodon-fossil-found-in-san-mateo-county-creek","status":"publish","type":"post","link":"https:\/\/nextcitydigest.com\/?p=8907","title":{"rendered":"‘Immaculate condition’: Rare mastodon fossil found in San Mateo County creek"},"content":{"rendered":"
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Brigid Lynch was walking through a redwood forest in the San Mateo County hills when she noticed something unusual, half-submerged in the flowing water through a creek: a big, smooth object that didn\u2019t look like any of the other rocks.<\/p>\n

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\u201cIt really stuck out,\u201d she said. \u201cI had no idea what it was. I thought maybe it was a mollusk or something, but that didn\u2019t make sense since it wasn\u2019t near the ocean.\u201d<\/p>\n

She took some photos, went home and entered them in Google photo search to solve the mystery. Lynch had made a remarkable discovery \u2014 she found a huge and surprisingly well-preserved molar from a Pacific mastodon, an extinct species of prehistoric elephant that roamed western North America during the Ice Age.<\/p>\n

The 9-foot-tall creatures, which weighed up to 13,000 pounds with long tusks and hair, were common in California and other Western states from more than 2.5 million years ago until about 11,000 years ago, along with saber-toothed\u00a0tigers, camels, and other long-gone species. The tooth, a molar the size of a toaster, is one of the best preserved and most intact specimens ever found in the Bay Area, experts say.<\/p>\n

\u201cThe tooth itself is in immaculate condition. It\u2019s the most complete mastodon molar from our area, and the most spectacular mastodon molar that I\u2019ve ever seen,\u201d said Wayne Thompson, a paleontologist and owner of Pacific Paleontology, a consulting firm based in Santa Cruz County. \u201cI had chills and shivers up and down my spine. I was super happy to see this discovery because it can teach us a lot about the creatures themselves as a species and about this particular area. It\u2019s another puzzle in the Ice Age saga that we can put into place.\u201d<\/p>\n

Lynch, a geomorphologist, made the discovery in March when the company she works for \u2014 Balance Hydrologics, based in Berkeley \u2014 was doing research as part of an effort to restore endangered red-legged frogs for the Midpeninsula Regional Open Space District.<\/p>\n

The district isn\u2019t saying exactly which of its preserves or what creek the molar was found in.<\/p>\n

\u201cWe don\u2019t really want people digging around in the creek looking for other fossils,\u201d said Ryan McCauley, a district spokesman.<\/p>\n

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But he said it has inspired staff members at the agency, which owns a network of 26 preserves covering more than 70,000 acres in San Mateo and Santa Clara counties.<\/p>\n

\u201cMy imagination goes to \u201cJurassic Park,\u201d with big ferns and dinosaurs,\u201d McCauley said. \u201cBut this isn\u2019t that. This is only about 10,000 years ago, when there were mammoths and saber-toothed\u00a0tigers in the Bay Area. It isn\u2019t that long ago. It boggles the mind.\u201d<\/p>\n

After Lynch realized she had discovered a mastodon molar, she asked colleagues who were out in the same forest if they could find it. They did, putting it in a bucket to bring it back. The company called experts at Stanford University, who also brought in Thompson. They confirmed it did indeed come from a mastodon, and today the fossil sits in Stanford University\u2019s Doerr School of Sustainability\u2019s collection.<\/p>\n

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Researchers plan to use carbon dating and other techniques to determine its exact age, the mastodon\u2019s diet and the local climate conditions when it lived.<\/p>\n

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\u201cIt\u2019s pretty rare to just stumble across a fossil like this,\u201d said Christine Garcia, specimen collection curator and manager for the Doerr School collection. \u201cMost of these finds come from construction projects. For Brigid to have the eye to see this and know it is something special, that\u2019s rare and unique.\u201d<\/p>\n

Every few years, a major fossil discovery surfaces, she noted, such as in 2013 when workers rebuilding the dam at Calaveras Reservoir dug up a trove of prehistoric fossils, including teeth from huge megalodon sharks, whale skeletons, and hippo skeletons from 15 to 20 million years ago during the Miocene epoch, when the East Bay was covered by a shallow, tropical-like inland sea. Those fossils are now at UC Berkeley\u2019s Museum of Paleontology.<\/p>\n

Garcia said the mastodon tooth, which was sitting in the forest for thousands of years before the Roman Empire or before Egyptians built the pyramids, is not being displayed to the public. It\u2019s currently in a temperature-controlled room at Stanford, where it is slowly drying out and being monitored, she said. Curators also have not put chemicals or other preservatives on it, which is common to preserve bones and fossils, for now, so it can be researched first.<\/p>\n

\u201cBecause of how well-preserved it is, I don\u2019t think it has been sitting in the creek the whole time,\u201d Garcia said. \u201cIt probably washed out from somewhere more recently, like a hillside further upstream. When we get storms, there will be large slumps of land that can wash out at once. That\u2019s often a time when fossils become exposed.\u201d<\/p>\n

Pacific mastodons are slightly different than mammoths. They had stockier body proportions and spent considerable time in forests, while mammoths were mostly grassland animals.<\/p>\n

Although the Ice Age \u2014 15,000 or 20,000 years ago \u2014 is a recent period in geologic time, it was a world very different from today\u2019s. Because temperatures were cooler around the globe and much of the Earth\u2019s water was locked up in ice, sea levels were roughly 300-400 feet lower than today. San Francisco Bay was a valley, and the edge of the Pacific Ocean was more than 20 miles farther west than it is now. Mastodons and other animals could walk out to the Farallon Islands, across a vast plain that is now hundreds of feet below the ocean\u2019s surface.<\/p>\n

People lived nearby and hunted mastodons, bison and other Ice Age animals.<\/p>\n

\u201cThe Bay Area has been referred to as a Serengeti during the Ice Age, with plains and grasses and all kinds of animals roaming about, from mastodons to camels to saber-toothed tigers,\u201d Garcia said. \u201cHumans overlapped with these animals. They did not overlap with dinosaurs. This is a different, more recent time period. But\u00a0 particularly fascinating to think about what our area must have been like.\u201d<\/p>\n

Mastodons are believed to have eaten many of the same trees, like alders, that exist in the area today. Lynch said she sent photos of the huge tooth to lots of friends and family.<\/p>\n

\u201cI have never found anything like this before,\u201d she said. \u201cI\u2019m terrible at finding cool rocks in the field. This was really unique. I was sharing it with everyone in my life. Everyone was so stoked. They texted their families. It really spread. It\u2019s a once-in-a-lifetime thing.\u201d<\/p>\n

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A well-preserved mastodon molar found in a San Mateo County creek offers rare insights into Bay Area Ice Age history.<\/p>\n","protected":false},"author":1,"featured_media":8906,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-8907","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"yoast_head":"\n‘Immaculate condition’: Rare mastodon fossil found in San Mateo County creek - Next City Digest<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/nextcitydigest.com\/?p=8907\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"‘Immaculate condition’: Rare mastodon fossil found in San Mateo County creek - Next City Digest\" \/>\n<meta property=\"og:description\" content=\"A well-preserved mastodon molar found in a San Mateo County creek offers rare insights into Bay Area Ice Age history.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/nextcitydigest.com\/?p=8907\" \/>\n<meta property=\"og:site_name\" content=\"Next City Digest\" \/>\n<meta property=\"article:published_time\" content=\"2026-09-11T07:37:16+00:00\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"6 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/nextcitydigest.com\\\/?p=8907#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/nextcitydigest.com\\\/?p=8907\"},\"author\":{\"name\":\"admin\",\"@id\":\"https:\\\/\\\/nextcitydigest.com\\\/#\\\/schema\\\/person\\\/13065d40d633843429ac57d4e5c06f9b\"},\"headline\":\"‘Immaculate condition’: Rare mastodon fossil found in San Mateo County creek\",\"datePublished\":\"2026-09-11T07:37:16+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/nextcitydigest.com\\\/?p=8907\"},\"wordCount\":1140,\"commentCount\":0,\"image\":{\"@id\":\"https:\\\/\\\/nextcitydigest.com\\\/?p=8907#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/nextcitydigest.com\\\/wp-content\\\/uploads\\\/2026\\\/09\\\/b331d870f7db8660c4f2e77dda6cd214.webp\",\"articleSection\":[\"News\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/nextcitydigest.com\\\/?p=8907#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/nextcitydigest.com\\\/?p=8907\",\"url\":\"https:\\\/\\\/nextcitydigest.com\\\/?p=8907\",\"name\":\"‘Immaculate condition’: Rare mastodon fossil found in San Mateo County creek - 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