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 relat
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Contact: Greg Lester
glester@nsf.gov
703-306-1070
National Science Foundation
18-Nov-1998