# New study on single-asteroid extinction theory



## j d worthington (Dec 1, 2006)

Okay... just for the sake of passing on information, here's the the latest I've seen:

Single massive asteroid wiped out dinosaurs: study - Yahoo! News

However, the final part of the story indicates this is still being questioned ... Does anyone else have anything further on this?


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## Urien (Dec 1, 2006)

Interesting...

Did you see that Hawking was saying we need to get off the planet eventually the other day? One of his fears was the asteroid with our name on it.

Here's a link.

Telegraph | News | We must leave Earth, says Hawking


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## Pointfinder (Dec 1, 2006)

Cool links thanks for sharing them.  I hope they develope that matter/antimatter space ship soon, I know a few people I'd like to volunteer for the first trip, he, he.


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## j d worthington (Dec 1, 2006)

Thanks for the link, Andrew. Yes, I've seen him express concerns about this before, and many (I'm one) tend to see the same problem. It's the old thing about "putting all your eggs in one basket"; frankly, we need to get busy building more baskets.....


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## bowerbird (Jan 23, 2007)

As far as I am aware there are more than one theory to fit the multiple mass extinctions.

The supervolcano theory is one


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## The Ace (Jan 23, 2007)

When I was at University in the early 'nineties, the asteroid impact would have been laughed out of court. Then it suddenly became sexy again and they found the impact crater.  Now, from being accepted, it's suddenly a matter for debate, but there's an asteroid out there with our name on it.
  I know that increased seismic and volcanic activity in the Upper Cretaceous (caused by continental shift, including the formation of the Himalayas), was a major factor in the extinction events around that time, but another factor was probably the rise of the flowering plants, many of which were believed to be toxic to contemporary herbivores.  Although the last dinosaurs vanish at the KT boundary, there is ample evidence for a protracted decline beginning in the Mid Cretaceous. 
   I have always found the single impact theory a bit too neat and it gives no hint to the causes of other mass extinction events, whereas the opening and closing of Tethys, with subsequent disruption in weather and oceanic current patterns, is clearly a factor in both the  Permian and Cretaceous events.  The bottom line is that  we don't know the entire story, so it's best to keep an open mind.


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## Homer Hoose (Mar 2, 2007)

The Ace said:


> I have always found the single impact theory a bit too neat and it gives no hint to the causes of other mass extinction events, whereas the opening and closing of Tethys, with subsequent disruption in weather and oceanic current patterns, is clearly a factor in both the  Permian and Cretaceous events.  The bottom line is that  we don't know the entire story, so it's best to keep an open mind.


Yes it's best to keep an open mind. But big events have big effects and the last big event was the last Ice Age which gave birth to modern man  who likes to speculate on past events like the impact effect of the Chicxulub asteroid.

The hundred mile wide crater in the Gulf of Mexico speaks well to a big event so the only question remaining is whether or not the dinosaurs were  already on the road to extinction when Hell came to Earth and administered the coup de grace to the oversized  monsters.


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## Delvo (Mar 3, 2007)

The Ace said:


> I have always found the single impact theory a bit too neat and it gives no hint to the causes of other mass extinction events


Actually, some of the others are associated with other impacts. And the only explanations that anybody's come up with for why the mass extinctions seem to happen at nearly regular intervals are external... things that would cause such impacts to repeatedly become more likely, then less likely, then more likely...


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## HardScienceFan (Mar 18, 2007)

The Ace said:


> When I was at University in the early 'nineties, the asteroid impact would have been laughed out of court. Then it suddenly became sexy again and they found the impact crater. Now, from being accepted, it's suddenly a matter for debate, but there's an asteroid out there with our name on it.
> I know that increased seismic and volcanic activity in the Upper Cretaceous (caused by continental shift, including the formation of the Himalayas), was a major factor in the extinction events around that time, but another factor was probably the rise of the flowering plants, many of which were believed to be toxic to contemporary herbivores. Although the last dinosaurs vanish at the KT boundary, there is ample evidence for a protracted decline beginning in the Mid Cretaceous.
> I have always found the single impact theory a bit too neat and it gives no hint to the causes of other mass extinction events, whereas the opening and closing of Tethys, with subsequent disruption in weather and oceanic current patterns, is clearly a factor in both the Permian and Cretaceous events. The bottom line is that we don't know the entire story, so it's best to keep an open mind.



Sounds like U know what you're talking about
Further hints: Sedimentology,2003
Journal of Iberian Geology,31(2005),www.ucm.es \JIG,
the volcano theory has as its principal proponent Vince Courtillot.


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## mosaix (Mar 18, 2007)

andrew.v.spencer said:


> Interesting...
> 
> Did you see that Hawking was saying we need to get off the planet eventually the other day? One of his fears was the asteroid with our name on it.
> 
> ...



AVS remember Baldrick in Blackadder III?

_*Blackadder*: "What are you doing?"

*Baldrick*: "I'm carving my name on this bullet"

*Blackadder*: "Why?"

*Baldrick:* "Well they say that there's a bullet somewhere with your name on it. I thought that if I owned it there was less chance of me being shot by it."

_I wonder if NASA have considered this as a possible strategy?


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## gigantes (Mar 18, 2007)

i read something interesting the other day about the alligator group- it seems they do not have the traditional sex chromosomes to determine which will be males and which, females.  instead, _the temperature of the nest apparently determines their sex._

this means that you could have one nest a little closer to the water and it would turn into all females.  and you could have another nest a little more inland and it would be all males.  also, you might have a nest where the warmer temperatures inside turned the inner eggs into males and the cooler temps on the outside turned the edge eggs into females.

alligator eggs apparently also have some other mechanisms to balance out this process, otherwise a prolonged cold period or warm period would cause extinction due to the population being all males or all females (with no parthenogenesis available).

so one theory about the dinos is that due to the long period of uniform weather, they did not develop those additional mechanisms to balance sex-determination, and when the climate suddenly cooled they were left with a big problem.

the alligator group came before them and outlasted them, of course.


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## j d worthington (Sep 6, 2007)

And the latest news story on this subject:

Distant space collision meant doom for dinosaurs - Yahoo! News

Titled: "Distant space collision meant doom for dinosaurs", from Reuters, by Will Dunham, datelined Wed., Sept. 5, 2007.


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