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Re: Impact QUestion - Re: The birds vs. the pterosaurs



Tyrberg Tommy wrote:
> 
> 
> 1) Many organisms (e. g. trees, hibernating animals) have complex mechanisms
> for surviving winter which require extensive physiological and behavioral
> preparations, usually triggered by seasonal cues. A winter "out of season"
> would be disastrous for these.
> 
> 2) Winter is usually a season of extreme stress and a severe bottleneck for
> high-latitude organisms. Most probably do not have the capability to survive
> a winter of much greater duration or severity than normal. For example most
> trees would be killed by drought if a winter was greatly prolonged since
> they cannot absorb moisture when the ground is frozen.
> 
> Tommy Tyrberg

I keep coming back to the 535 AD event. There are multiple lines of
evidence (tree rings, historic accounts, etc) that point to no sunlight
for up to 18 months in Europe, and because the eruption probably occured
in February (that's when the Chinese accounts mention an all-mighty bang
somewhere to the south) which is late winter in the northern hemisphere,
winter conditions would have lasted about two years. In places like
Siberia colder than average conditions continued for about 10 years. And
yet as far as we know, no species became extinct. With no sun light
there was no evaporation, and hence no rainfall for at least 18 months.
Conditions were hard - but things managed to survive. I think we don't
give life on earth as much credit as it deserves. You don't survive a
couple of billion years unless you have a few tricks up your sleeve. :)

-- 
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Dann Pigdon                   Australian Dinosaurs:
GIS Archaeologist           http://dannsdinosaurs.terrashare.com
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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