LOS ANGELES (AP) — Surrounded by a gooey
graveyard of prehistoric beasts, a small crew diligently wades through a
backlog of fossil finds from a century of excavation at the La Brea Tar
Pits in the heart of Los Angeles.
Digs over the years have unearthed
bones of mammoths, mastodons, saber-toothed cats, dire wolves and other
unsuspecting Ice Age creatures that became trapped in ponds of sticky
asphalt. But it’s the smaller discoveries — plants, insects and rodents —
in recent years that are shaping scientists’ views of life in the
region 11,000 to 50,000 years ago.
‘‘Earlier excavations really
missed a great part of the story,’’ said John Harris, chief curator at
the George C. Page Museum, which oversees the fossil collection. People
‘‘were only taking out bones they could see, but it’s the hidden bones
that provide clues to the environment.’’
The museum on Monday celebrates
100 years of digging, which has recovered some 5.5 million bones
representing more than 600 species of animals and plants, the richest
cache of Ice Age fossils.
There’s so much left to do that it
could easily take another century to complete. On a recent Wednesday, a
volunteer in a white lab coat pounded away at a bison skull in the
museum’s fishbowl laboratory where visitors can witness paleontology in
action. Nearby, two workers hunched over microscopes, sorting bone
fragments belonging to extinct creatures.
In the back storage,
floor-to-ceiling shelves of wooden crates house bones that need to be
cleaned, identified or labeled. The museum estimates it has 100,000
specimens to catalog and another million to scrub.
Long before skyscrapers towered
over Wilshire Boulevard, giant beasts ruled the land. Back then,
sagebrush scrub covered the basin, home to herds of mammoths, bison,
camels and ground sloths. Mastodons hung out in the woodlands. Lurking
were meat-eating predators including saber-toothed cats, dire wolves and
giant jaguars.
Every so often, creatures would
get bogged down in pools of water and asphalt that seeped from
underground crude oil deposits, and die of dehydration or starvation.
Stranded animals that appeared to be easy prey then became a trap for
predators that also got stuck in the ooze.
In 1913, the predecessor to the
Natural History Museum of Los Angeles County launched a two-year project
to uncover only the best-preserved mammal bones, largely ignoring
everything else. Though the early digs gave scientists a glimpse into
the types of animals that roamed, there was still much to be learned.
After the early missteps,
scientists in 1969 decided to focus on pulling everything out and
revisited a tar pit dubbed Pit 91 to do a more detailed excavation. For
nearly 40 years, work at Pit 91 dominated the Page Museum’s efforts as
visitors gawked from a viewing platform.
Museum officials temporarily
halted digging at Pit 91 several years ago to concentrate on an
unexpected trove of Ice Age fossils that was found during the
construction of an underground garage next to the tar pits, located some
7 miles west of downtown Los Angeles.
‘‘I can’t think of any other site
that is as rich,’’ said Sarah George, executive director of the Natural
History Museum of Utah.
Every time a foundation is dug,
‘‘more old blocks of tar filled with fossils came out of the ground,’’
said George, who used to work as a curator at the Natural History Museum
of Los Angeles County.
Despite a century of digging,
scientists still can’t agree on how the Ice Age beasts became extinct.
Some suggested that the prehistoric predators may have competed with
humans for similar prey and that carnivores ate carcasses out of
desperation. But Larisa DeSantis of Vanderbilt University said dental
studies of saber-toothed cats and other carnivores suggest they were
‘‘living the good life’’ before they became extinct.
Museum excavators plan to leave some fossils buried — in case better tools are invented to study them in the next century.
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