A Summer in the Pits : Fossils: Each year at Hancock Park, volunteers dig up more clues about life on prehistoric Earth.

The stirring sounds of “Raiders of the Lost Ark” filled the air as the fossil-hunters climbed one last time out of Pit 91, the nation’s only regularly excavated tar pit.

Every summer since 1984 volunteers have pulled Ice Age fossils from the bowels of Hancock Park. As chief excavator Eric Scott explained, it’s traditional to end each successful season by playing the music associated with Indiana Jones, the movie hero who makes the hot, tedious work of excavation look glamorous. A wrap party with pizza and beer is also planned.

The haul from this summer’s dig, which ended Sunday, was 552 specimens, including thefossilized bones of long-extinct saber-toothed cats, dire wolves and Ice Age condors, caught in the gooey asphalt that has been trapping animals for at least 40,000 years.

That was considerably fewer than last season’s total of 746 animal and plant specimens, Scott said. But it included an unusually large number of big bones.

On Sunday, volunteer Gary Takeuchi, a geology student at Cal State Los Angeles, removed the season’s prize, a finely preserved dire wolf skull. Its worn teeth indicated an animal that had managed to beat the ancient odds and survive until old age. “Spectacular,” Scott called the find.

Originally excavated almost a century ago, the tar pits constitute one of the richest caches of Ice Age fossils in the world. Preserved by the asphalt that ensnared them, 550 species of plants and animals have been recovered from more than 100 sites in the Hancock Park area.

The summer dig has been an annual event since it began in 1984 to coincide with the Olympics. A $6,000 budget only allows for a nine-week dig. Summer is the preferred time, Scott explained, because the asphalt softens in the heat and more volunteers are available.

According to Christopher A. Shaw, who coordinates the summer dig for the George C. Page Museum of La Brea Discoveries, one reason Pit 91 was reopened in 1969 was to redress the bias of early paleontologists toward large remains, called macrofossils.

Of the more than 1 million specimens removed from the tar pits by early excavators, less than 1% were of plants or animals smaller than a rabbit, Shaw said. Unlike the pits’ first excavators, today’s scientists treasure insect parts and other microfossils. These small remains often reveal more about the ancient environment than large finds do, in part because small creatures tend to stay closer to home than large ones.

Although fossilized pollen may be a boon to science, it typically doesn’t get the adrenaline pumping like coming upon a mastodon bone.

“We were taking out saber-toothed cat bones that were bigger than the bones in my body,” said Scott, 28. “It was a thrill.”

Wearing rubber boots, hard hats and their grubbiest clothes, the first pair of 18 volunteers began digging July 5, 13 feet down in a 28-by-28-foot pit redolent of asphalt. A tarp protected them from the sun but allowed the public a clear view from the observation station at ground level. As each fossil was painstakingly removed, some with dental picks, Scott made careful field notes, including a record of exactly how each specimen was positioned when found. The note-taking isn’t sexy but it’s crucial, he indicated. The excavator has to preserve information, such as a bone’s orientation, that the dig itself destroys, preserving data to answer questions that may not have been asked yet.

Sabertooth bones were especially plentiful this year, Scott said. Evidence of four different individuals was uncovered, including one whose water-worn bones suggest that the animal may have died somewhere else and been swept to the site by an ancient stream.

The saber-toothed cat, whose skull appears on T-shirts that only volunteer excavators are allowed to buy and wear, has been extinct for 10,000 years and is especially interesting because nothing quite like it now exists.

Scott said this summer’s finds included four sabertooth atlases, the top vertebra of the neck. The boomerang shape of the neck bones bolsters the theory that the ferocious sabertooth had a much more powerfully muscled neck than such contemporaries as the North American lion, whose atlas was smaller and more compact.

Information about the 552 newly found specimens will end up in the Page Museum’s growing data base on Pit 91, Scott said.

Data on 48,000 specimens already taken from Pit 91 are now being computerized. The project will give scientists instant access to information that, in the past, was sometimes buried again in the museum’s files.