Her Old Bones Have Rested Long Enough

Construction workers in Moorpark recently uncovered the skeleton of a fossilized mammoth that is estimated to be at least 400,000 years old. The skeletal pieces were covered in plaster for protection and moved to a Santa Ana laboratory for temporary storage.

Question: Who found the skeleton?

Answer: A bulldozer operator uncovered the fossil and nicked one of the animal’s tusks while grading on a 350-acre construction site north of downtown Moorpark on March 29. Trevor Lindsey, the on-site paleontologist hired by developer William Lyon Homes, halted work on part of the site until he could bring in more scientists to help with the excavation. It took nine days to remove the skeletal pieces, which included two legs, ribs, part of the skull, a 7-foot portion of one tusk, the tip of another, two of the animal’s four teeth, including one still attached to the lower jaw, and a shoulder blade. It is believed the animal was comparable to a 46- or 47-year-old elephant of today.

Q: How was the skeleton removed and transported off-site?

A: A team of up to eight paleontologists used heavy tools such as jackhammers and shovels and more delicate instruments, including dental picks, to remove dirt and rock around the fossil. The dig area was mapped and each piece was photographed before being covered in a protective layer, including tin foil and gauze. Then the pieces were coated with sheets of burlap soaked in fast-drying plaster. These cast-like “jackets” were then moved with the help of a backhoe and later a crane, which lifted the specimens onto a 22-foot flatbed truck for the trip to the lab.

Q: Who owns the skeleton?

A: The city of Moorpark retains ownership of the fossil based on its development agreement with William Lyon, according to Hugh Riley, assistant city manager. The developer is constructing 265 homes in the foothills a mile north of City Hall and must pay for removing, transporting and preparing the bones for further study and eventually delivery to a museum, most likely the Natural History Museum of Los Angeles County.

Q: How will its age be calculated?

A: Two methods will be used to date the fossil, which was found in a stack of rock layers made of sediment deposited by streams 400,000 to 2.5 million years ago.

First, the mammoth’s teeth and jaw will be measured and examined -- along with bones from its feet -- to help pinpoint the exact species. With that information, the animal’s age can be estimated.

Second, 3,000 pounds of sediment that surrounded the fossil will be screened for other bones, especially those of rodents, which can help gauge the mammoth’s age. Paleontologists will try to recover fossil pollen from the sediment to learn what plants were growing in the area to help reconstruct the ancient climate and environment. Sediment stuck to the animal’s teeth may help determine what it ate just before it died.

Some of the rock will be sent to Occidental College, which has a modern paleomagnetics lab that will determine the polarity of the sediment. The earth’s magnetic field has reversed periodically in the past (causing compass needles to point south), the last time about 780,000 years ago. The shift can be measured magnetically, which would help determine if the fossil is at least that old.

Q: Are such prehistoric finds rare in California?

A: John M. Harris, chief curator of the Page Museum at La Brea Tar Pits, said much of California is sedimentary rock that could yield ancient fossils. “However, complete or semi-complete skeletons of anything are always rare,” he said.

Occidental College geology professor Donald Prothero said “all fossil mammals are rare,” but early indications suggest this mammoth is even more primitive than the Columbian mammoths from the Ice Age found so far.

Experts believe this is a female Archidiskodon meridionalis, or southern mammoth, thought to have entered the southern part of the United States about 1.4 million years ago, which is considered quite rare. Only five other fossil sites with this type of mammoth have been reported in Southern California, according to Bruce Lander, president of Paleo Environmental Associates, the private environmental consulting firm handling the recovery. Fossils of the late Cretaceous through Pleistocene epochs (from 10,000 to 80 million years ago) have been found in the general vicinity of Moorpark, Lander said.

Q: Are developers required to hire paleontologists?

A: Yes, builders are required under the California Environmental Quality Act of 1970 to protect fossils and prehistoric artifacts on a construction site. The law requires them to monitor grading, salvage fossils and conserve them in an appropriate repository.

In this case, Moorpark officials required a paleontologist on site during construction in case fossils were found.

Q: What will happen to the remains now?

A: Until the fossil is handed over to a museum for permanent safekeeping, it will remain at the Santa Ana laboratory of Paleo Environmental, which will clean the bones -- using compressed air and tools such as a hand-held miniature jackhammer and whiskbroom -- to remove sediment. Some of the bones will be treated with chemicals to harden and preserve them. The skeletal pieces will then be measured, photographed, labeled and cataloged.

After the private lab completes its preparation of the bones, which could take about two months, it will make fiberglass molds of several of the large fossil portions, for creating replicas for exhibit. Eventually, the bones will be placed in special crates or cartons and trucked to a museum.

The remains may go into storage, where researchers would be able to study them, said Harris at the Page Museum. “It is entirely possible, however, that they might be placed on display temporarily

Q: What do scientists hope to learn from this particular fossil?

A: A close examination of the fossil can provide details on the animal’s shape and what it looked like. The bones could reveal how it died. Study of the surrounding sediment should provide information about the area’s ecosystem and climate about a million years ago. “This kind of information is very relevant to our current concerns about global warming and how that will affect the environment in which we live,” Harris said.