Mastodon’s Tooth? Yes, Can You Dig It? : Chance Find Spurs Search for Fossils at Site in Corona

A million years ago, give or take a few, a mastodon feasted on the vegetation that grew along the banks of the Santa Ana River.

A couple of weeks ago, a part of that prehistoric mammal reappeared when a heavy-equipment operator found its fossilized tooth at a Corona clay mine.

And since then, a paleontologist from the University of California has found other fossilized evidence of Corona’s prehistoric residents, including rodent teeth and a horse femur.

The find will give scientists not only a look at prehistoric life in the area but also new insight into the geologic history of this part of Southern California, said Michael Woodburne, a professor at UC Riverside.

More Believed Buried

Woodburne believes that more animal remains are buried in the clay deposits and hopes to be able to spend more time digging at the site.

While it is “impossible to tell,” from the few bones found so far, what other animals roamed the area a million years ago, Woodburne said, “you could find a camel; you could find fossils (of) deer.”

“If you find herbivores,” he suggested, “you might find some of the carnivores that ate them. . . . A saber-toothed tiger might be lurking around somewhere.”

That prospect fascinates Bob Wiens, one of two owners of the property where the bones were uncovered. “I’m excited to find it (the tooth) here,” Wiens said. “. . . I think there is a lot of history to be learned here, and I want to open it” to further scientific exploration.

Finds at Other Sites

Other fossilized bones, many of them much older than those found in Corona, have been uncovered in the Southland: at the La Brea Tar Pits in Los Angeles, in the Cajon Pass north of San Bernardino and at San Timeteo Canyon in central Riverside County, Woodburne said.

Although the Corona find has not yielded any unique specimens, it will help geologists learn more about the history of the Santa Ana River and Santa Ana Mountains, the professor said. “The age of these rocks is not otherwise well-known,” he said.

Because the bones were found about five miles from the river’s current course, Woodburne said, “you would have to say it was a fair bit wetter, in terms of climate,” a million years ago.

Much of what is now Corona probably was part of a much more active Santa Ana River, he said.

Tooth Reconstructed

William Daily, a UC Riverside staff research associate--or, in his words, a “bone janitor”--has carefully reconstructed the mastodon tooth from its three major fragments, and mounted them in plaster to make a mold to cast copies.

“If we have a cast,” he explained, “we can send it to another institution” for comparison with other specimens. Such comparisons could help confirm the UC Riverside scientists’ estimate of the fossils’ age, he said.

The researchers also need to make a cast for their collection, Woodburne said, because the property owners have asked them to return the tooth.

“This is where they came from,” Wiens said. “. . . It’s more meaningful if they stay in the city.” So he and his partner, John Bremer, plan to donate the specimens to Corona, to display at the Civic Center or Public Library.

Property Work Delayed

They also are willing to delay work on the property temporarily to allow Woodburne to seek more bones. One piece of bone is already visible in some freshly cut earth, Wiens said.

He said the owners are most concerned with keeping vandals from making off with such specimens, and keeping sightseers out of the mine.

“We don’t want a lot of people out here digging,” Wiens said. “We want the university to do it.”

The property eventually will be developed into an industrial park, he said. Now it is supplying clay to cap the Riverside County landfill in east Corona.

As long as the property owners can meet their commitments to the county, they will accommodate the paleontological dig “as long as people can learn something from this,” Wiens said.

“This is just the beginning,” he said, gesturing to a few bleached bone fragments, sitting atop a wall of red clay. “I think there is a lot more here.”