Fossil Graveyard : Dump Yields Jawbone of New Species of Prehistoric Monkey in Dig Sponsored by L.A. Museum

Scientists digging at a Simi Valley dump have uncovered the fossilized jawbone of a previously unknown monkey thought to be as old as 50 million years.

The discovery represents the latest of about 40 species of primates found in North America, said David P. Whistler, curator of vertebrate paleontology at the Los Angeles County Museum of Natural History.

“It’s rare,” Whistler said. “And man is always interested if he has cousins.”

The jawbone of the extinct primate, similar to a lemur, was found near a parking lot at the Simi Valley Landfill, where 200 acres of sloping sand blankets both garbage and the Sespe rock formation, one of the world’s richest sources of fossils.

“It really sparks our interest,” said Bruce Lander, a research associate at the Museum of Natural History and a consultant for Waste Management Inc., which owns the landfill. “You’re not supposed to find our primitive relatives in a place like this.”

Lander and others have unearthed the fossil remains of more than 130 species, ranging from rats to ancient rhinos, in the layers of sand and red clay carved from the landfill’s periphery to cover 1,200 to 2,000 tons of garbage each day.

But the jawbone from the adult monkey, found in a sand heap near the parking lot and next to a sign that reads “Bird Control Gun Used at Disposal Area,” is the group’s most significant relic. No one had found a new primate species in Simi Valley since 1928.

Tom Kelly, a Chatsworth veterinarian and part-time paleontologist, has proposed in a research paper to name the new species after Mark Roeder, the scientist who dug up the inch-long row of blackened teeth in early May. Kelly theorized that the species was a primate--and a new one--based on the cusps and cutting edges of the teeth. Authorities at the Los Angeles museum agreed with him.

Kelly and Roeder, both of whom are also research associates at the museum, have been sifting through the landfill for 10 years.

In fact, paleontologists have been scouring the area since the turn of the century. But during the last year, Waste Management has sponsored the research as part of a mitigation plan required by state law to protect fossil resources before the landfill’s proposed expansion.

Largest U.S. Collection

The Museum of Natural History, which houses the largest vertebrate fossil collection in North America, and Engineering-Science, a consulting firm based in Pasadena, have collaborated with Waste Management in the project.

Malcolm McKenna, curator of vertebrate paleontology at the American Museum of Natural History in New York, considers the Simi Valley dump one of the world’s most abundant fossil sites.

“A landfill covers up goodies, but sometimes the bulldozers can bring fossils up,” McKenna said. “That would be a very large number for any site to find 130 species.”

Nearly 35 rock layers in the landfill are packed with bone fragments from land mammals that evolved between the evolutionary periods known by paleontologists as the Uintan and the Duchesnean.

“This is one of the few places in the entire world where you have this particular time period,” Kelly said. “Almost every bed is producing fossils.” But fossil hunting is not the only scientific activity in the unlikely laboratory.

While paleontologists rake the sand for skeletal remains, geologists from USC are combing the landfill for reverse-polarity rocks that may have once been scattered through Central American jungles.

The poles of the Earth shift, said Steve Lund, a geophysicist at USC. A rock can register each shift like a compass, based on the latitude line at which it lies. Since scientists know the general dates of polar changes, they can measure the magnetism in a rock to find out where it has traveled.

Lund and Yi Lu, a USC graduate student from China, think that Simi Valley--and the land west of the San Andreas Fault and south of the San Gabriel Mountains--slid northward from the area of southern Mexico 50 million to 200 million years ago.

Continental Drift

The geologists and paleontologists at the dump are comparing notes to find out where the Simi Valley area originated.

“We integrate our data and support one another,” Lander said.

Despite the rewards for both parties, the work is an exercise in pain. Sometimes Kelly spends eight hours on his knees, finding rodent teeth by poking through millimeters of sand with a needle. During the summer, a thin row of eucalyptus trees provides the only shade. Constantly present is the sour aroma of trash.

“It’s hot, it’s dusty, it’s tedious, it’s back-breaking, which is why I consider myself an office paleontologist,” said Lander, who prefers to do his research in the cool halls of the museum.

In most areas of the dump, the diggers collect hundreds of pounds of rock. They soak the rock in buckets of kerosene and water to separate bones from the red clay.

Then, like prospectors, they pour the silt onto a screen. Any suspicious lumps are sent to the museum for cleaning and, finally, identification.

Lander said most of the bones are “things that may not look very spectacular but have a wealth of information for the paleontologist.” Although the landfill has not yet yielded an early human skull or the spinal column of a brontosaurus, the number of fossils--especially new species such as the Roeder primate--has made the dump a Sutter’s Mill for paleontologists. And some even relish the slow, agonizing work.

“I love being outdoors and digging in the dirt,” Kelly said, “plus the excitement that any minute you might find an animal that no human being has ever seen before.”