is it possible that 65 million years ago, a gamma ray burst killed all the dinosaurs?

The best bets for the mass extinction at the Cretaceous-Tertiary boundary are either an impact with a large object such as an asteroid, or a period of massive vulcanism, or perhaps both. However, some have proposed a GRB as a contributor to the mass extinction even at the end of the Ordovician period.

Nick

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Nick Theodorakis

What Nick said.

Though I'd like to add that it's probably an impact. Not an asteroid impact, however, but a comet - which is loads more effective. It's basically said to have struck the Earth at an incredible speed some 65 million years ago, killing about 70% of the living creatures that ruled the Earth back then (which were mainly the dinosaurs). The other 30% were killed off due to the huge amounts of dust caused by the impact. This dust is thought to have spread all over the sky and blocked out sunlight for weeks, resulting in the death of the rest of the dinosaurs.

If I'm not mistaken, the comet hit an area somewhere in between North America and South America; near Mexico. And the impact still exists today.

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Fiery Phoenix. The controversey over the K/T boundary arose over the anomalous levels of iridium in the soil samples. Iridium is fairly rare in comets but far more common in asteroids prompting Luis Alvarez to suggest an asteroid impact. As the layers were worldwide and thickened towards Central America...that became the smoking gun. Oil prospectors recalled seismic evidence for a crater off the coast of Oaxaca, and it fit pretty well, prompting well deserved fame for Luis. pete


see:http://en.wikipedia.org/wiki/Chicxulub_crater

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A. Lomonosov

Thanks for the correction.

I do remember reading that it was a comet, though, because an asteroid is not strong enough to cause such a great event. But with the information you provided, I take that back.

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"Science is physics and astronomy." -Me
"There is absolutely no law in physics that prevents time travel." -Dr. Michio Kaku

I heard there was Iridium at the KT boundary, and that is why Alvarez thought that an object from outside earth crashed. Where else could that Iridium layer come from?

thoth Volcanic eruptions...not as common there either. pete

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A third rate theory forbids.
A second rate theory explains after the fact.
A first rate theory predicts.
A. Lomonosov

the 6 mi. dia. asteroid striking at chixilub (sp?) is being attributed with the dino-destruction as it was the worst location to have happened at. I think the claim is there was lots of sulfur bearing stone there as well as being on the coast. No telling what a smack like that could do to vulcanism around the world as well. Evidently, something that big was able to start fires world wide from returning materials crashing around the world.

Whether it was the sole cause or not may forever be uncertain. It seems plausible and IMHO, a great example of the scientific method at work. Since it's at the crossroads of a number of different disciplines, I expect there will always be some conflicting views that will probably all exist as 'mainstream'.

There's been recent discoveries of other impact craters roughly the same age as the one in Chicxulub, meaning it may have been several blows, on top of other problems the dinosaurs were facing that eventually knocked them all out.
Except for birds, obviously.

Even then, large classes of primitive birds such as the Enantiornithes ("opposite birds") didn't make it either.

Nick

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Nick Theodorakis

Cool, hate to say it but didn't know about that particular branch.