Buckyballs to replace amalgam for filling material .... 
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 Buckyballs to replace amalgam for filling material ....

Buckyballs to replace amalgam for filling material ....


Study shows asteroids destroyed life on Earth at least twice

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - Asteroids crashing into Earth have virtually wiped
out life not once but at least twice, scientists have reported.

An asteroid or comet roughly the same size as the one that wiped out the
dinosaurs 65 million years ago did even worse damage 250 million years ago,
experts found in a report published in Friday's issue of the journal
The evidence comes from space gases trapped in little carbon spheres called
Buckyballs in ancient layers of sediment. They show the Permian extinction
event, during which most species on the planet disappeared, started with a
cosmic collision.

"The impact ... releases an amount of energy that is basically about 1
million times the largest earthquake recorded during the last century,"
Robert Poreda, associate professor of earth and environmental sciences at
the University of Rochester in New York, who worked on the study, said in a

The comet or asteroid would have to have been 4 to 8 miles (6.5 to 13 kms)
across. The jolt roused volcanoes, which buried huge areas in lava and sent
up ash to join the dust from the explosion to plunge the world into
centuries of unnatural dark and cold.

Trilobites -- strange,{*filter*}roach-like creatures that once ruled the
planet -- died out completely, all 15,000 species of them. Ninety percent of
all marine creatures and 70 percent of land vertebrates went extinct.
"If the species cannot adjust, they perish. It's a survival-of-the-fittest
sort of thing," said Luann Becker, assistant professor of Earth and Space
Sciences at the University of Washington, who also worked on the paper.
"To knock out 90 percent of organisms, you've got to attack them on more
than one front."

The asteroid which wiped out the trilobites was just about the size of an
asteroid that left a giant crater on Mexico's Yucatan Peninsula 65 million
years ago and wiped out the dinosaurs.
Unlike with the Yucatan impact, the researchers, who included teams from the
National Aeronautics and Space Administration and New York University, do
not yet know where the giant space object smacked down.

What they did find was a layer of little carbon molecules called
buckminsterfullerenes, or Buckyballs. Inside these soccerball-shaped spheres
were helium and argon gases.
The spheres, gathered at sites in Japan, China and Hungary, lay at the
sedimentary layer put down 250 million years ago, between the Permian and
Triassic periods.
"These things form in carbon stars. That's what's exciting about finding
fullerenes as a tracer," Becker said.
The gases are isotopes, meaning they have a certain atomic structure, that
suggests they came from space, the researchers reported.
They fit in with other evidence found from layers dating back to the
extinction. For instance, some of the most extensive volcanic activity ever,
in what is now Siberia, laid down enough lava to cover the entire planet
with 10 feet (three metres) of rock over a one-million year period.
"It was the proverbial blast from the double-barrelled shotgun," Poreda
said. "We're not sure of all the environmental consequences, but with both
the impact and with the volcanic activity, we do know that Earth was not a
happy place. It may be that the combined effects of impact and volcanism are
necessary to cause such a tremendous extinction."
But life did come back, giving rise to the rich collection of animals that
thrived during the Triassic, Jurassic and Cretaceous periods. Dinosaurs
evolved, as did mammals.
"These two extinctions are like bookends for the age of the dinosaurs,"
Poreda says. "The P/T (Permian/Triassic) boundary helped to usher in the age
of the dinosaurs, and the K/T (Cretaceous/Tertiary) boundary snuffed it

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