NATIONAL CITY — Remains of a camel, a mastodon and other mammals unearthed during freeway construction last week are helping scientists understand what Southern California was like during the Ice Age.
"This site is a piece of the puzzle in figuring out the distribution of mammals that lived here," said Tom Demere, assistant curator of paleontology at the San Diego Natural History Museum.
A week after an earth-grading machine operator discovered the first prehistoric bone, paleontologists were still eagerly uncovering fossils from the Pleistocene epoch, 10,000 to 120,000 years ago.
Among the remains dug up so far at the California 54 freeway construction site are half of the skeleton of an ancient horse, including five vertebrae, some ribs and leg bones.
"I'm not going to leave until we find the skull--I'll dig this mountain away," said Richard Cerutti, one of five Natural History Museum paleontologists working at the site.
Other mammal remains being encased in plaster for transport to the Natural History Museum are a tooth from another horse, part of a mastodon tusk, the jaw and limb bones of a fossil gopher, limb bones and a fragment from the lower jaw of a fossil camel and vertebrae of what may be a fossil bison.
At night, security guards are posted to keep an eye out for fossil thieves.
"There are people drooling to get their hands on this stuff," said Caltrans spokesman Jim Larson.
Paleontologists have documented ancient bones at four sites over the last week on a hilly area along California 54. Excavators have yet to dig around the tusk remains of a mastodon that were found just feet behind a house.
"Wherever the earth is turned up and you find sedimentary rocks there's a good chance that fossils will be found there," Demere said.
Until now, most of the Ice Age fossils found in the county have been of marine animals uncovered near bays and estuaries, Demere said. A few scattered bones from Ice Age mammals have been found inland, but never has one site in the county's coastal area produced so many mammal fossils from that period.
But the find pales in comparison to the famed La Brea tar pits in Los Angeles, which include extensive remains of Ice Age mastodons, elephants, camels, ground sloths and saber-tooth cats. Some discoveries in Orange County have also been more extensive, Demere said.
The Natural History Museum has a $15,000 contract with Caltrans to look for fossil remains as Caltrans widens the freeway.