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View Full Version : Were the Dinosaurs Really Wiped Out by an Asteroid? Possibly Not



Fraser
2009-Apr-27, 10:40 AM
In 1979, the huge Chicxulub crater, measuring about 180 km (112 miles) in diameter, was discovered on the northern Yucatan Peninsula, Mexico. Scientists made the obvious conclusion that something rather large had hit the Earth in this location, probably causing all kinds of global devastation 65 million years ago. At around the same time, 65% [...]

More... (http://www.universetoday.com/2009/04/27/were-the-dinosaurs-really-wiped-out-by-an-asteroid-possibly-not/)

geonuc
2009-Apr-27, 10:48 AM
Hmmm ... kinda sounds ATM. ;)

Wizard From Oz
2009-Apr-27, 10:59 AM
Hmmm ... kinda sounds ATM. ;)

Not really, there has been increasing doubt that the asteroid was the cause. A study a couple of years ago showed that speciation of dinosaurs was crashing even though the biomass was remaining stable, if that makes sense.

As the article points out, the Deccan Traps were making a mess of the environment, and I believe the asteroid was just one more thing on the dinosaurs plate rather than the primary cause.

hhEb09'1
2009-Apr-27, 12:58 PM
Not really, there has been increasing doubt that the asteroid was the cause. There have been arguments on both sides from the beginning. Gerta Keller, one of the authors of that paper, has been one of the main participants for decades. Scientific American published a "point/counterpoint" in October of 1990--Alvarez (Walter) and Asaro defended their hypothesis, and Vincent Courtillot defended the Deccan Traps idea.

The Universe Today article makes it sound like the crater was discovered, and that led researchers to suggest that the dinosaurs were killed by an impact. But the Alvarezes came up with their theory without the benefit of the knowledge of Chicxulub--according to the wiki article (http://en.wikipedia.org/wiki/Chicxulub_crater) it was discovered by petroleum geologists who couldn't release the information. There has been a lot of speculation over the years whether Chicxulub actually is the smoking gun.

I'd post a comment on the UT article, but the login seems to be different from the BAUT login, and I don't have one there. I guess I could get one.

Sticks
2009-Apr-27, 01:00 PM
Well we can be sure this time it was not a certain person in a certain building acting alone :whistle:

Meanwhile, I came in to post this link (http://www.dailymail.co.uk/sciencetech/article-1173846/Bang-goes-theory-Dinosaur-extinction-occurred-300-000-years-AFTER-asteroid-impact.html), and found I had been Toseeked :doh:

Wizard From Oz
2009-Apr-27, 02:17 PM
The Universe Today article makes it sound like the crater was discovered, and that led researchers to suggest that the dinosaurs were killed by an impact. But the Alvarezes came up with their theory without the benefit of the knowledge of Chicxulub--according to the wiki article (http://en.wikipedia.org/wiki/Chicxulub_crater) it was discovered by petroleum geologists who couldn't release the information. There has been a lot of speculation over the years whether Chicxulub actually is the smoking gun.

Yes you are right. The Alvarezes never claimed that was the crater. Their research was about the iridium they found at th KT boundary which started the whole ball rolling. One of the major attractions of this strike though was the extensive sulphur desposits that are believed to have been churned up by the impact. Just one more thing to add to dinosauia misery.

Interstingly enough if this crater is a bit old, that actually fits some evidence better. It would go a long way towards the sudden drop in speciation which was something on the order of 70% over the last million years of dinosaur existence.

Losing bio-dversity would have been a huge blow for the species to try and radiate back into environmental niches. Maybe mammals gained enough ground to compete

nokton
2009-Apr-27, 05:09 PM
Not really, there has been increasing doubt that the asteroid was the cause. A study a couple of years ago showed that speciation of dinosaurs was crashing even though the biomass was remaining stable, if that makes sense.

As the article points out, the Deccan Traps were making a mess of the environment, and I believe the asteroid was just one more thing on the dinosaurs plate rather than the primary cause.
Yes they were, and without the asteroid, they were history, thanx Wizard. Nokton

hhEb09'1
2009-Apr-27, 05:17 PM
As the article points out, the Deccan Traps were making a mess of the environment, and I believe the asteroid was just one more thing on the dinosaurs plate rather than the primary cause.Yes they were, and without the asteroid, they were history, thanx Wizard. NoktonThe information in the OP has the impact 300,000 years before.

Still, nothing rules out the possibility that a crater somewhere else was the actual culprit--and there's always the possibility that the crater is completely subducted. It has been 65 million years, after all.

glenfallswv
2009-Apr-28, 12:02 AM
Gerta Keller seems to be doing the Ponz and Fleishmann approach to science. I was intrigued a few years back when I saw trailers for a Discovery science show claiming evidence that meteors did not do in the dinosaurs. I watched only to find that she just cackled at other honest researchers and claimed there was a SECOND impact. She did not refute other evidence, and did not cover existing evidence better than existing theory, and did not make predictions that would confound existing theory. She only proposed that there was another impact. That's certainly possible given the example of the 'string of pearls' breakup of SL9 but the crater should've left something. If you claim that the second impact was off the Pacific coast and has since been subducted away there should still have been a second KT layer.

I guess that the second impact theory was dropped due to incredulity. So now we should go back now to the earlier Deccan hypothesis as though it were new? The Chixulub hypothesis has been more accepted because it explains more facts. Go dig way away from the Yucatan. The KT boundary is more clear cut and unmixed. Out there is clearer and more pristine evidence that the boundary closes the book without being so close to the expected sediment reversals that muddies the waters. I suppose folks might say I should wait for the journal article and see what evidence is offered. I say if we spend too much time reinvestigating the cold fusions of this world, we don't have time for more worthy theories.

Next time this comes up, unless they've got some cogent rebuttals, put it in the "your own personal theory" section of UT and the Forums.

GOURDHEAD
2009-Apr-28, 03:01 AM
Come on fora mongers It had to be prions specific to the dinosauria aided and abetted by our mammalian direct progenitors.

TampaDude
2009-May-05, 08:05 PM
Clearly, it was all Bush's fault.

Sticks
2009-May-06, 04:32 AM
Clearly, it was all Bush's fault.

Please re-read the rules, especially concerning the No Politics rule