How a ranger stumbled upon one of the biggest fossil finds in California history

How a ranger stumbled upon one of the biggest fossil finds in California history

ismagine a California with erupting volcanoes to the east and Los Angeles buried under the Pacific Ocean. Giant camels, rhinos and miniature four-tusked elephants graze in a lush landscape, only to be preyed upon by bone-crushing dogs.

This is the prehistoric scene evoked by a treasure trove of new fossils unearthed in the Sierra foothills of California – an extremely important find and one of the most important in the history of the state.

The find, on a huge expanse of virgin land maintained by the East Bay Municipal Water District (EBMUD), prompts scientists to scramble to piece together bone fragments that they say tell a story of climate change from d ‘five to 10 million years ago.

The discovery began last summer, when Greg Francek, a water district ranger, spotted a funny rock with markings vaguely resembling bark, during a routine patrol of 28,000 acres of EBMUD lands on the eastern edge of the Central Valley of California.

It turned out to be a petrified tree. Francek searched further and found a whole grove of petrified trees, then realized that the area was strewn with thousands of bone fragments.

A tapir jawbone. Photograph: East Bay Municipal Utilities District

“It started with the fact that I was in the right place at the right time and had an eye for something that was out of place,” said Francek, who is a ranger and naturalist for the district of water for 10 years. “I had no idea what I was looking at was actually the remains of great beasts that had walked in this area millions of years ago.

Soon, scientists unearthed fossils throughout a zoo of prehistoric animals that existed in the era known as the Miocene. This was over 50 million years after dinosaurs roamed the continent and it would be millions of more years before humans appeared. It was a time when behemoths roamed North America. Volcanic activity and shifting geological plates had not yet formed the Sierra Nevada, and most of southern California was still underwater.

Russell Shapiro, professor of geology at California State University, Chico, said that when Francek first took him to the area, which is spread over several miles on land closed to the public, he was amazed at how many fossils different animals appeared in the same place. .

“Greg was showing me these places and we were like, ‘Oh my God, that’s a horse; it is a camel; it’s a rhinoceros; it’s a turtle, ”he said. “Everything was fine there.

Prehistoric Miocene fauna. Photography: Mauricio Anton / Scientific photo library

Shapiro and other scientists began a detailed excavation and study of the results, under the enthusiastic supervision of the Water District. “It’s pretty unique,” ​​Shapiro said. “It’s an extremely rich site.”

Although a lot of research remains to be done to understand the skeletal fragments, they have already made several exciting discoveries, including the bones of horses which may have had three toes and giant camels with giraffe necks which would have allowed them to eat. over 20 feet. trees.

One of the most common animals at the site appears to have been gomphotheres, elephant-like creatures with four tusks, two above and two below their mouths, described as being small enough to “enter through the mouth. front door”. Scientists also found the remains of a fish up to four feet long and the almost intact skull of a mastodon with tusks. They also found bone fragments from tapirs, turtles and birds.

Predator remains were more difficult to find. Researchers have found a few yet-unidentified bone fragments from carnivores. But tooth marks found in some of the other bones and some petrified feces suggest the grazing animals may have been hunted by the wild dogs known to have roamed North America at the time. One type was the fierce bearded dog, which could grow up to 8 feet long. Another extinct breed was the Borophagus, or the bone-crusher dog, which hunted or scavenged large grass-eaters and then munched on their bones for nutrient marrow.

A scientist and a student chisel the mastodon's tusks.
A scientist and a student chisel the mastodon’s tusks. Photographie: Jason Halley / California State University, Chico

The results suggest a large pasture, with herbivores feeding on a lush landscape that in times passed from forests to prairies.

“We’re still trying to figure out who’s who at the zoo,” said Francek, who said there was a lot to learn about the species unearthed at the site.

Shapiro said the fossil discovery provides a glimpse of a time when the planet’s climate was shifting from a warmer period to a cooler period, and in California, dense forests were turning to grasslands. While it is not clear whether the creatures all lived at the same time or over successive generations, it is possible that the animals were all trapped in a volcanic mudslide, he said.

“The whole planet started to cool down at that point, which eventually led to ice ages,” Shapiro said. “What’s really cool about this site is that you can see classic forest creatures as well as prairie creatures. “

A turtle shell.
A turtle shell. Photograph: East Bay Municipal Utilities District

The Water District, which provides water to 1.4 million people living in the East Bay Area of ​​San Francisco, is careful not to reveal the exact location of the site for fear people will disturb him or loot him. But EBMUD has prepared an online tour of the results for classrooms and the public.

The fossils are transported to the state of Chico, where students have the opportunity to help prepare them for further study by a wide range of scientists. Eventually, the materials will be transferred to the Museum of Paleontology at the University of California at Berkeley, where they can be displayed and viewed by researchers around the world.

Shapiro and Francek both said they were delighted that EBMUD wanted to preserve and study the results.

“What an opportunity to rekindle people’s interest in science again,” Shapiro said. “People are so interested when they realize what’s in their own backyard.”


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