By Kate Kelland, Health and Science Correspondent
LONDON (Reuters) - A giant asteroid smashing into Earth is the only
plausible explanation for the extinction of the dinosaurs, a global
scientific team said on Thursday, hoping to settle a row that has
divided experts for decades.
A panel of 41 scientists from across the world reviewed 20 years' worth
of research to try to confirm the cause of the so-called
Cretaceous-Tertiary (KT) extinction, which created a "hellish
environment" around 65 million years ago and wiped out more than half of
all species on the planet.
Scientific opinion was split over whether the extinction was caused by
an asteroid or by volcanic activity in the Deccan Traps in what is now
India, where there were a series of super volcanic eruptions that lasted
around 1.5 million years.
The new study, conducted by scientists from Europe, the United States,
Mexico, Canada and Japan and published in the journal Science, found
that a 15-kilometre (9 miles) wide asteroid slamming into Earth at
Chicxulub in what is now Mexico was the culprit.
"We now have great confidence that an asteroid was the cause of the KT
extinction. This triggered large-scale fires, earthquakes measuring more
than 10 on the Richter scale, and continental landslides, which created
tsunamis," said Joanna Morgan of Imperial College London, a co-author of
The asteroid is thought to have hit Earth with a force a billion times
more powerful than the atomic bomb at Hiroshima.
Morgan said the "final nail in the coffin for the dinosaurs" came when
blasted material flew into the atmosphere, shrouding the planet in
darkness, causing a global winter and "killing off many species that
couldn't adapt to this hellish environment."
Scientists working on the study analyzed the work of paleontologists,
geochemists, climate modelers, geophysicists and sedimentologists who
have been collecting evidence about the KT extinction over the last 20
Geological records show the event that triggered the dinosaurs' demise
rapidly destroyed marine and land ecosystems, they said, and the
asteroid hit "is the only plausible explanation for this."
Peter Schulte of the University of Erlangen in Germany, a lead author on
the study, said fossil records clearly show a mass extinction about 65.5
million years ago -- a time now known as the K-Pg boundary.
Despite evidence of active volcanism in India, marine and land
ecosystems only showed minor changes in the 500,000 years before the
K-Pg boundary, suggesting the extinction did not come earlier and was
not prompted by eruptions.
The Deccan volcano theory is also thrown into doubt by models of
atmospheric chemistry, the team said, which show the asteroid impact
would have released much larger amounts of sulphur, dust and soot in a
much shorter time than the volcanic eruptions could have, causing
extreme darkening and cooling.
Gareth Collins, another co-author from Imperial College, said the
asteroid impact created a "hellish day" that signaled the end of the
160-million-year reign of the dinosaurs, but also turned out to be a
great day for mammals.
"The KT extinction was a pivotal moment in Earth's history, which
ultimately paved the way for humans to become the dominant species on
Earth," he wrote in a commentary on the study.
(Collins has created a website here which allows readers to see the
effects of the asteroid impact.)
(Editing by Myra MacDonald)
C Thomson Reuters 2010.
It took 30 years for this scientific theory to go from a radical
hypothesis to accepted science. That's a bit slower than average, even
-- Steven L.
> Morgan said the "final nail in the coffin for the dinosaurs" came when
> blasted material flew into the atmosphere, shrouding the planet in
> darkness, causing a global winter and "killing off many species that
> couldn't adapt to this hellish environment."
Shouldn't that be "Helish environment," since it was cold?
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
"Why aren't resurrections from the dead noteworthy?" -- Jim Rutz
"Lotta soon to die punks here." -- igotskillz22
> "The KT extinction was a pivotal moment in Earth's history, which
> ultimately paved the way for humans to become the dominant species on
> Earth," he wrote in a commentary on the study.
Humans are not the dominant species on Earth.
The experts seem to be divided on the issue;
We should ask "Theresa Manyan" she is the only one who can settle the
Are you taking into account the history of plate tectonics?
Also, if you consider the acceptance of natural and random global
catastrophes are in opposition to the original concept of
uniformitarianism, the time period was even longer, at least 200
> On Fri, 5 Mar 2010 16:54:45 +0000, "Steven L."
> <sdli...@earthlink.net> wrote:
> > "The KT extinction was a pivotal moment in Earth's history, which
> > ultimately paved the way for humans to become the dominant species on
> > Earth," he wrote in a commentary on the study.
> Humans are not the dominant species on Earth.
Humans are the top predators.
Any visit to any supermarket will demonstrate how that works in
-- Steven L.
I, for one, welcome our prokaryotic overlords.
On the other hand, I challenge any other species to dispute my
dominance. If you're a member of another species, and want to claim
dominance over the earth, just respond to his message and we'll arrange
an appropriate competition.
Please withdraw your challenge; else wise DIG will have to let Madman
back into T.O.
No, he's human. Technically.
Perhaps there is *no* "dominant species" (singular).
Even given only three domains, is there a dominant domain?
Surely, God could have caused birds to fly with their bones made of solid gold,
with their veins full of quicksilver, with their flesh heavier than lead
The Crime of Galileo (1976) by Giorgio De Santillana, p. 167
I think that all living species today are "top" in some sense.
They have all survived to this point. Whether they survive
beyond this point is contingent on a number of things, many
of which are beyond their control.
--- Paul J. Gans