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Science and Technology "Somewhere, something incredible is waiting to be known." - Carl Sagan.

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Old June 12 2014, 09:33 PM   #1
varek
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extinctions possibly explained

A team of scientists at the Chinese Academy of Sciences, led by Yong Wei, have speculated that the Earth’s atmosphere may have lost millions of tons of oxygen during the Triassic-Jurassic magnetic pole reversal, about 200 million years ago.

[COLOR=#0000ff]http://blogs.discovermagazine.com/d-brief/2014/06/10/earths-magnetic-flips-may-triggered-mass-extinctions/#.U5nH4bFQZV-[/COLOR]

http://en.wikipedia.org/wiki/Triassic_Extinction

This could explain what made most land creatures go extinct then and could also explain what may have happened on Mars, if life existed there before such a cataclysmic event, that is.
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Old June 18 2014, 06:06 AM   #2
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Re: extinctions possibly explained

Great. Aren't we about due for one of these?
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Old June 18 2014, 06:16 AM   #3
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Re: extinctions possibly explained

If we are, I don't want to know about it.
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Old June 18 2014, 06:34 AM   #4
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Re: extinctions possibly explained

TayLaLaLa wrote: View Post
If we are, I don't want to know about it.
I don't buy it. It doesn't explain the extinctions that occurred in the ocean or the fact that the survivors were birds and mammals which have higher metabolic rates.
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Old June 18 2014, 06:39 AM   #5
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Re: extinctions possibly explained

I thought life was resilient rather than fragile. I agree.
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Old June 18 2014, 06:50 AM   #6
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Re: extinctions possibly explained

Boy, oh boy...if only we could Really slingshot around the sun...for my money, however, the theory of the Giant Meteor makes the most sense...so far...
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Old June 18 2014, 07:24 AM   #7
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Re: extinctions possibly explained

I don't think they've got the extinction trigger because they say that the oxygen levels only dropped by 4.5 percent from their modeled pole-reversal, for a total of 9 percent. I'm currently living in a city with 4.5 percent below-standard O2 partial pressure, and come from a town with about 9 percent less O2 partial pressure. Denver's oxygen levels are almost 18 percent below standard, and life there shows no signs of an eternal mass extinction.

Oxygen levels need to drop by about 40 percent before you really notice it, and by over 60 percent before adaptation takes more than a week or two.
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Old June 18 2014, 08:32 AM   #8
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Re: extinctions possibly explained

gturner wrote: View Post
Denver's oxygen levels are almost 18 percent below standard, and life there shows no signs of an eternal mass extinction.
Maybe not mass extinction, but I definitely noticed the lack of oxygen when I drove out to Colorado last year. I was exhausted for two full days before my body finally adapted to it.
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Old June 18 2014, 08:37 AM   #9
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Re: extinctions possibly explained

RoJoHen wrote: View Post
gturner wrote: View Post
Denver's oxygen levels are almost 18 percent below standard, and life there shows no signs of an eternal mass extinction.
Maybe not mass extinction, but I definitely noticed the lack of oxygen when I drove out to Colorado last year. I was exhausted for two full days before my body finally adapted to it.


...was there for a week in December, and will be again in August, and I could not help notice an increase in C2H5OH levels...including mine...also did notice a distinct shortness of breath, and also what looked like a TOTAL extintion of a certain age group...bodies everywhere...clothing torn...missing...it was a real sight to see...

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Old June 18 2014, 08:39 AM   #10
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Re: extinctions possibly explained

I have the answer to all of this. I will post tomorrow, after I've slept. It's late now.
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Old June 18 2014, 03:38 PM   #11
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Re: extinctions possibly explained

I am sceptical about this theory. A reduction of oxigen by 9% would merely mean a drop from 21% to approximately 19%. That's hardly a lethal level, considering that we can easily survive in crowded classrooms or meeting rooms which contain about 17% oxigen. Levels under 15% influence your ability to think, levels around 10% make you faint, less than 8% oxigen means you suffocate.

Even if dinosaurs were a little more vulnerable to oxigen reduction, it's still not all that likely that they all died.

Also, the instant the air loses oxigen, the levels are replenished by free oxigen from the oceans (it's a dynamic balance). So that the marine animals should have been effected just as strongly as the terrestrial ones. Which afaik they weren't.
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Old June 19 2014, 02:40 AM   #12
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Re: extinctions possibly explained

Okay...I promised to post "the answer" to the extinction of the dinosaurs...but I need to locate some material for my presentation. Bear with me...life's demands are putting a damper on revealing "the truth"!

So I guess you can treat this class as a study hall...so start making paper airplanes.
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Old June 19 2014, 04:04 PM   #13
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Re: extinctions possibly explained

LMFAOschwarz wrote: View Post
Okay...I promised to post "the answer" to the extinction of the dinosaurs...but I need to locate some material for my presentation. Bear with me...life's demands are putting a damper on revealing "the truth"!

So I guess you can treat this class as a study hall...so start making paper airplanes.
Darn...just got my grades...flunked
Study Hall and Paper Airplane Making...
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Old June 19 2014, 07:34 PM   #14
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Re: extinctions possibly explained

Rhubarbodendron wrote: View Post
I am sceptical about this theory. A reduction of oxigen by 9% would merely mean a drop from 21% to approximately 19%. That's hardly a lethal level, considering that we can easily survive in crowded classrooms or meeting rooms which contain about 17% oxigen. Levels under 15% influence your ability to think, levels around 10% make you faint, less than 8% oxigen means you suffocate.

Even if dinosaurs were a little more vulnerable to oxigen reduction, it's still not all that likely that they all died.

Also, the instant the air loses oxigen, the levels are replenished by free oxigen from the oceans (it's a dynamic balance). So that the marine animals should have been effected just as strongly as the terrestrial ones. Which afaik they weren't.
Remember that when speaking in the context of geologic time, that 9% reduction in oxygen would have occurred over the course of hundreds of thousands of years, and would have LASTED for half a million years, with the extinction event spread out over a similar timespan. That second point bears repeating: mass extinctions do not occur over a small number of lifetimes for the animals in question, and are only "sudden" in the context of geologic time.

The thing is, the reduction in oxygen means larger species will have, on average, slower metabolisms and reduced energy and vitality than their ancestors. Accordingly, they have shorter lifespans, produce less offspring and are slightly less aggressive throughout their lives. If they are out-competed for resources by smaller life forms better adapted to the lower oxygen levels, then this makes their lives even harder. A persistent drop in the birthrate of, say, 5%, coupled with a slight increase in the mortality rate would shrink the population of a particular species over time, and if the conditions that caused those new rates persists for half a million years, then they eventually die out.
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Old June 19 2014, 08:03 PM   #15
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Re: extinctions possibly explained

HIjol wrote: View Post
Boy, oh boy...if only we could Really slingshot around the sun...
You'd discover the hard way that's what triggers magnetic pole reversals.
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