NSF PR 98-75 - November 18, 1998
Media contact: |
Greg Lester |
(703) 306-1070 |
glester@nsf.gov |
Program contact: |
Richard Lane |
(703) 306-1551 |
hlane@nsf.gov |
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Scientist Finds Asteroid Fossil That May Have Caused
Global Dinosaur Extinction
The fossilized remnants of an asteroid that may have
caused the global extinction of dinosaurs and other
species more than 65 million years ago has been found
by a National Science Foundation (NSF)funded researcher.
Frank Kyte, a geochemist from University of California
at Los Angeles (UCLA), presents his analysis of the
fossil meteorite in the November 19 issue of the journal
Nature.
Some scientists believe that this particular worldwide
extinction, which ended the Cretaceous period 65 million
years ago, was caused by the destructive impact of
a comet or asteroid. Kyte found the fossil meteorite
while studying the sediment boundary layer between
the Cretaceous and Tertiary eras.
Hidden in mud and buried beneath the Pacific Ocean
for 65 million years, the fossil is no longer composed
of all of its original minerals, yet has retained
its original shape and texture.
"The fossil is a record of the original rock," said
Richard Lane, program manager in NSF's earth sciences
division, which funds Kyte's research, "much like
fossilized traces of dinosaur skin, or, more appropriately,
like casts made from the victims of Mt. Vesuvius at
Pompeii whose imprints were preserved in the volcanic
ash."
According to Kyte, it is likely that the fossil depicts
the remains of a colossal asteroid, some six miles
wide, which collided with the earth near Mexico's
Yucatan peninsula. His findings suggest that the original
meteorite had a rocky composition that corresponds
with the makeup of asteroids, as opposed to the porous
materials that would more likely be found in a comet.
Although the fossil itself is only a tenth of an inch
long, Kyte was able to deduce its origins using instruments
from UCLA's electron microprobe and neutron activation
laboratories. These instruments, which can identify
the chemical components of a given substance, found
the fossil to be high in iridium, an element found
in relative abundance in asteroid meteorites.
In our solar system, asteroids are found orbiting
the sun in a belt between Mars and Jupiter. This rocky
belt of space debris is thought to be a leftover from
the time when the planets first formed.
Kyte notes that this particular asteroid moved out
of the belt towards Earth at about 40,000 miles per
hour. The resulting impact is thought to have had
devastating consequences for the world's climate and
could have led to the extinction of the dinosaurs
and many other forms of life.
"Studies like Kyte's show that celestial impacts have
had a profound effect on the history of the earth,"
said Lane. "One begins to think that such catastrophic
events played at least as important a role in shaping
the earth as did more gradual processes."
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