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BBC Science's Helen Briggs
"Shockwaves travelled around the planet"
 real 28k

Thursday, 18 November, 1999, 07:56 GMT
Fiery end for dinosaurs?
Scientists believe the entire atmosphere may have burned

The dinosaurs may have been wiped out in a gas-fuelled firestorm, according to a new theory.

A "hell on Earth" may have been triggered by vast quantities of trapped methane released from under the ground by a comet.

A massive impact in the Gulf of Mexico 65 million years ago is thought to have changed the Earth's climate and driven the dinosaurs to extinction.

But a team of American oceanographers believe this is only half the story.

They say the dinosaurs' end may have been even more dramatic, as shock waves from the explosion released highly flammable methane from within the Earth.

At the end of the Cretaceous period huge amounts of the gas, generated by rotting vegetation, lay trapped in sediments 500 metres below sea level.

Bubbling up to the surface, the methane would have escaped into the air and been ignited by lightning bursts in the disturbed atmosphere, say the scientists.

Burton Hurdle, of the Naval Research Laboratory in Washington DC, told New Scientist magazine: "The atmosphere itself would have been on fire. This could have contributed to the demise of the dinosaurs."

Periodic escapes of gas

As evidence, the researchers point to an earlier discovery of disruption in late Cretaceous sediments at Black Ridge, off the coast of Florida, which may have been due to methane release.

As it may have been before the firestorm - BBC's Walking with Dinosaurs
A smaller "blow-out" is thought to have occurred in the Gulf of Mexico during the late Pleistocene epoch.

More recent activity on the ocean floor suggests trapped methane periodically escapes even without asteroid strikes.

Some scientists believe the Bermuda Triangle phenomenon could be explained by methane escaping and overwhelming passing ships or planes.

Dinosaur expert Dr Angela Milner, from the Natural History Museum in London, said many dinosaurs appear to have been in serious decline even before the impact.

But she agreed huge methane fires "could have been the final straw" for some species.

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See also:
11 Nov 99 |  Sci/Tech
'Striking' dinosaurs found in Sahara
03 Nov 99 |  Sci/Tech
Biggest dinosaur identified
20 Oct 99 |  Entertainment
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