Mammoth tooth found at Transbay dig S.F. Development

Mammoth remains and a piece of gold are displayed for the media on Wednesday, September 12, 2012, after construction crews digging on the site of the Transbay Terminal in San Francisco, Calif., have unearthed the remains of a wooly mammoth. less Mammoth remains and a piece of gold are displayed for the media on Wednesday, September 12, 2012, after construction crews digging on the site of the Transbay Terminal in San Francisco, Calif., have unearthed ... more Photo: Carlos Avila Gonzalez, The Chronicle Photo: Carlos Avila Gonzalez, The Chronicle Image 1 of / 8 Caption Close Mammoth tooth found at Transbay dig 1 / 8 Back to Gallery

(09-13) 12:36 PDT San Francisco -- A seemingly ordinary day at the Transbay Transit Center construction site became a mammoth day of discovery Monday when a mild-mannered crane operator reached deep into the earth and pulled out a tooth.

This was no ordinary tooth. The 10-inch-long brown, black and beige chomper, broken in two and missing a chunk, once belonged to a woolly mammoth, an elephantine creature that roamed the grassy valley that's now San Francisco Bay 10 to 15 thousand years ago in the Pleistocene epoch.

Other woolly mammoth fossils have been found in the Bay Area, including in San Francisco about 2 miles away on Columbus Avenue, near Twin Peaks and in Hunters Point, said Jim Allen, a paleontologist and geologist for the project. The tooth, he said, is in remarkable condition with the enamel still intact, and has not deteriorated to the point of most fossils.

"It's a significant find," he said Wednesday. "It's unique to find something right smack in downtown San Francisco."

A sharp-eyed crane operator, Brandon Valasik, made the discovery while excavating a 200-foot deep hole inside a steel casing for one of the 181 pilings that will form a buttress wall for the massive transit center. Digging through a layer of dark sand about 110 feet down, he plucked out a scoop of soil and dumped it on the ground. He noticed something that looked like a rock but had an unusual shape and color.

"It looked too perfect to be a rock," he said.

Valasik stopped digging and examined his discovery. He called over a boss who took pictures and sent them to Allen. Later in the day, Valasik said, he was told that what he found once sat in the mouth of a woolly mammoth.

"I've been to Washington, D.C., to the Smithsonian," where he saw a woolly mammoth skeleton, he said, "but I never expected to find part of one."

Co-workers have since taken to calling him "Manny," an animated mammoth in the "Ice Age" movies.

Excavation work in the area was halted while the find was examined, but Allen said that because of the depth of the discovery, it's unsafe and unrealistic to send someone down to inspect the site, so digging was allowed to continue. But Allen and construction crews are keeping an eye on the diggings. Transbay officials say they also believe they may have discovered a jaw.

"This behooves us to continue digging," he said. "We might find more."

While he hasn't had time to do much research on the tooth, Allen said it appears to be from a Columbian mammoth, a relative to the modern elephant. Woolly mammoths were common in the Bay Area during the Ice Age, he said, a time in which there was no bay and the Pacific Ocean was far away. He likened it to Africa today.

"It was a zoo here," he said. "Mammoths, mastodons, short-faced bears, saber-toothed cats, they were all hanging out. ... If you could go back to the Bay Area 10, 15 thousand years ago, it would be a pretty wild scene."

Allen said the tooth, from the same age as specimens found in the La Brea Tar Pits in downtown Los Angeles, will aid scientists in the study not only of evolution and extinct species but of geology and tectonic forces that cause earthquakes. The tooth will probably be donated to the California Academy of Sciences, though the Transbay Transit Center may put it on display.

Construction crews have made other finds while excavating the foundations for the Transbay Transit Center. A couple of years ago, they unearthed artifacts from working-class Irish neighborhoods that filled the area in the 1800s, along with a small gold nugget.

"We're not only building the future," said Maria Ayerdi-Kaplan, executive director of the Transbay project. "We're preserving the past."