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Re: fyi Permo-Triassic Extinction



> >The collision wasn't directly responsible for the extinction
> >but rather triggered a series of events, such as massive
> >volcanism,

Doubt it. Nothing to add to the discussion a few weeks ago.

> >and changes in ocean oxygen, sea level and climate.

In sea level? How?

> >That in turn led to species extinction on a wholesale level,
> >according to the team.
> >
> >"If the species cannot adjust, they perish. It's a survival-
> >of-the-fittest sort of thing," said Becker, UW acting
> >assistant professor of Earth and Space Sciences.

Sigh... another one who hasn't understood what an impact is like. Adapting
to impact condition is impossible anyway. It's a survival-of-the-luckiest
sort of thing!

> >"To knock out
> >90 percent of organisms, you've got to attack them on more
> >than one front."

Plasma shockwave, humongous earthquake, hypercane, global forest fire, acid
rain, cold, darkness, heat... and so on. All with a single direct cause,
impact.

> >The scientists do not know the site of the impact 250 million
> >years ago, [...] However, the space body left a calling card --
> >complex carbon molecules called buckminsterfullerenes, or
> >Buckyballs, with the noble gases helium and argon trapped
> >inside the caged structure. [...]
> >
> >The researchers know these particular Buckyballs are
> >extraterrestrial because the noble gases trapped inside have
> >an unusual ratio of isotopes, [...]

OK, that's enough. This is proof positive that there WAS an impact. =8-)
=8-) =8-)

> >The researchers
> >estimate the comet or asteroid was roughly 3 3/4 to 7 1/2
> >miles (6 to 12 kilometers) across, or about the same size as
> >the asteroid believed responsible for the extinction of the
> >dinosaurs 65 million years ago.

Only?!?!? If the Shiva crater is real, there was a second impactor at the
K-T that was much bigger (though slower)...

> >Scientists have long known of the mass extinction 250 million
> >years ago, since many fossils below the boundary -- such as
> >trilobites, which once numbered more than 15,000 species --
> >diminish sharply close to the boundary and are not found above
> >it. There also is strong evidence suggesting the extinction
> >happened very rapidly, on the order of 8,000 to 100,000 years,
> >which the latest research supports.

A resolution of 8000 years? Cool...

> >Previously, it was thought that any asteroid or comet
> >collision would leave strong evidence of the element iridium,
> >the signal found in the sedimentary layer from the time of the
> >dinosaur extinction. Iridium was found at the Permian-Triassic
> >boundary, but not nearly in the concentration as from the
> >dinosaur extinction. Becker believes that difference is
> >because the two space bodies that slammed into Earth had
> >different compositions.

Or, maybe more probable, the impactor was so big that the explosion was so
enormous that most of the material was blasted back into space ("the
self-cleaning impact").

BTW, I've -- yabbadabbadoo -- got
Donald F. Glut: Dinosaurs. The Encyclopedia. Supplement 1, McFarland
"2000"!!!