Scientists hope ancient Tomales Bay mammoth molar holds clues to prehistoric environment

TOMALES BAY

The color caught her eye first - pale, like bleached driftwood, against the darker rocks on the beach below the tideline. Sarah Warnock, a biologist, recognized the texture of fossilized bone when she bent to touch it.

What intrigued her was a slender, hand-shaped form poking its joined “fingers” through the stones and seaweed, as if in gesture - “Hey, there’s more here!” she said, recounting the moment.

Several calls and emails later, and Warnock had confirmed her hunch that an ancient relic had been uncovered on these shores. What she spotted on the beach that late August day was the fragile, fossilized pieces of a mammoth molar from prehistoric times.

James Allen, a licensed geologist and paleontologist who helped to unearth the Ice Age fossil, says the exciting find represents more than just “a cool mammoth tooth.” It could help him and others piece together more about the periods of warming that punctuated the long reign of our glaciated past.

It also could shed light on the history of the landscape that gave birth to Tomales Bay, a long, narrow saltwater inlet bisected by the San Andreas Fault. The bay floor there now was once part of a valley miles inland from the ocean.

“Finds like this are the bedrock of science,” said Robert Davies, a geology professor at Merced College who will be collaborating on the study of the Tomales Bay fossil. “It’s just interesting to learn about the past life and geologic story - about the ‘fossil zoo’ that we all live above. But more than that, scientifically, finds like this are important because fossils can help us determine the environments that were present when the animal was alive.”

Mammoths are among the most iconic creatures of the Last Ice Age, existing alongside sabertooth cats, giant horses, mastodons, giant ground sloths and other animals during a frozen period that dates back roughly 2.6 ? million years and lasted until just 11,700 years ago.

Columbian mammoths, the most common type in North America, are believed to have died out around 10,000 to 13,000 years before recorded history.

Locally, the ancestors of elephants are thought to have been among numerous long-extinct beasts who roamed broad coastal prairies that extended out beyond the Farallon Islands, now 27 miles offshore.

This theory of a “California Serengeti,” as posited by Breck Parkman, a Sonoma County resident and California State Parks senior archaeologist, is supported by numerous mammoth remains already discovered at various places around the county. They include sites in Santa Rosa, Glen Ellen, Valley Ford, Graton, and on the Estero de San Antonio near Bodega Bay, as well as in Bodega Bay itself, where a mammoth tusk and lower jaw with an attached tooth were found near Bodega Head in 1972.

Each one, said Parkman, “is another clue to the puzzle,” even though thousands remain undiscovered.

Warnock discovered the new specimen while walking on the rocky beach at the Audubon Canyon Ranch’s Cypress Grove Preserve near Marshall, where she resides with her husband, Nils, director of conservation science at the Cypress Grove Research Center.

It was upside down in a thick layer of clay beneath the rocky crust of the beach in an area covered by water at high tide. Its multi-pronged roots apparently had been exposed by the waves in recent months.

Though trained as an ornithologist, Sarah Warnock has had a longtime fascination with paleontology and had seen mammoth fossils up north during her work in Alaska, where they are fairly common.

Little of the tooth was visible above the beach surface, but she “recognized it right away” and set about contacting a paleontologist. She received confirmation through the Museum of Paleontology at UC Berkeley and from others that her find appeared to be a mammoth tooth. It is still undetermined whether the fossil is from a Columbian or a smaller woolly mammoth less common in these parts.

Fragments of the tooth already were breaking off when Warnock found it, lending urgency to the task of removing it from the beach. She packed the area with sand and rocks to prevent any more pieces from washing away.

Removing the toaster-sized fossil from its resting place last week proved challenging, given its fragile state. It’s clay bed was holding it together.

But Allen spent hours over two days excavating around it at low tide and squirting specialized liquid epoxy onto the surface to help hold the exposed parts together. He then lifted the entire clay-caked unit into a large ice chest - “a cooler of science,” Allen called it - where it would be taken away for careful and meticulous cleaning and examination at a later date.

The fossil was found in what appears to be native clay, in part of a geologically young sliver of earth amid a broad expanse of much older rock 80 to 200 million years old, James said.

There’s a possibility tiny microfossils found in the clay could reveal ocean elements that provide clues about when saltwater first came into the area to form Tomales Bay.

But Allen said he’s especially intrigued by the “layer-cake geology” in the area where the fossil was found and what it might say about what was happening during the mammoth’s era.

A near embankment may hold further clues. It shows layers of rock that would have overlain the clay where the tooth was found. That rock layer may have been formed by a violent rush of water like a “like a roaring river or a glacial outwash,” James said. The suggestion is that sometime soon after the mammoth lost its tooth and, maybe, died - in a pond, marsh or brackish lagoon - a river system “came blasting in at high velocity, as evidenced by the surge of heavy gravel,” James said.

“That’s a climate change signature,” he said.

If material from the fossilized tooth can be dated with enough precision, it might contribute to experts’ shared understanding of the dynamics that shaped the planet, James said.

“Earth is about 4.6 billion years old,” Davies said. “Life didn’t arrive robustly until only 600 million years ago. The fossils from the past 600 million years give us insight into extinct life forms, connections between extinct animals and those alive today, and record a fingerprint of Earth’s drastically changing climate.”

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com.