Fossil Find Reveals Ancient California Life

Construction of the missing link in the state’s power transmission system has produced a startling discovery of a different sort: a cache of fossils from a prehistoric grassland so rife with wildlife that scientists have dubbed it California’s ancient Serengeti.

Paleontologists excavated a shallow 6-foot-wide by 100-foot-long stretch of hilltop being graded for a high-voltage tower to find a bone bed containing 30 mammal species, including a new type of earth-digging weasel, a jumbo predatory bear-dog, half-pint camels, a rhinoceros, giant tortoises and five varieties of Hobbit-sized horses.

The fossil discovery was made a year ago when a construction crew was helping erect power transmission towers along Path 15, the notorious electricity bottleneck that became a focal point for public scorn during California’s energy crisis.

The collection of fossils unearthed so far are scheduled to travel this week to UC Berkeley, where they will be stored and displayed at the university’s Museum of Paleontology.

J.D. Stewart, a Pasadena paleontologist who led the subsequent dig last summer for Jones & Stokes, a Sacramento environmental consulting company, said it represents one of the most significant finds involving mammal fossils from the Middle Miocene Epoch, which stretched from 15 million to 18 million years ago.

Stewart said the bone bed is the most complete and undisturbed collection of land animals from that epoch since a UC Berkeley professor published a paper on a trove of Miocene-era fossils.

“We haven’t seen anything like this in about a century,” Stewart said.

Experts believe the large number of species found at the site, in the hills on the west side of the San Joaquin Valley, about 20 miles north of Coalinga, suggests that herds of the various species roamed a vast grassland peninsula near what was an inland sea covering much of what is now the Central Valley.

Several species of three-toed horses that have never before been found in California were discovered. Standing 3 feet tall at the shoulder, the tiny horses were no bigger than a Shetland pony

A small camel found in the bone bed also had never been discovered in the state.

The site also yielded hulking bear-dogs, huge carnivores standing 4 feet at the shoulders and firmly fixed at the top of the food chain. The beasts have been found before in the Mojave Desert, but never before in the Central Valley, Stewart said.

The weasel, meanwhile, is the first of its type ever discovered, and is believed to be an early predecessor to the badger or wolverine.

Investigators have work to do to comb through the bones of a variety of bird species, and Stewart suggested that several new types could still be discovered among the more than 1,200 fossils recovered.

And, he said, paleontologists have just scratched the surface.

Stewart speculated that a vast reservoir of other fossils remains at the site. Paleontologists went only 6 inches deep, leaving deeper levels and more of the turf for future scientists to explore as they develop new insights and techniques.

“It has basically been banked scientifically,” he said. “We take a little now, and leave more for later.”

Stewart and other paleontologists are seeking grants to continue their work on the fossil bed, which has been covered to protect what remains.