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Re: Meteor May Not Have Destroyed Dinosaurs Afterall?

Hello List, Debaters,

As to nickel poisoning  we are likely  in the "right church but wrong pew", so
to speak. Nickel may still have effected the eco-system but other compounds seem
to have played a larger part.  A source of  "toxin" came from the ground rock in
the region. There were various compounds released into the atmosphere and ground
as I recall.  Chuxilub was actually a very bad place to hit as the rocks there
given to a metamorphism which releases toxic compounds.  I can not recall
exactly the list of the compounds and explain why those rocks were so potent. I
have done a brief search online for Chuxilub and can't find my reference. 
Roughly (...very roughly....), the impact shock released  either a cyanide (CN)
and/or hydrogen sulfide . The hydrogen sulfide, of course, became a very
sulfuric acidic rain/fog.  Animals which could not leave or burrow had to
breathe sulfuric acid. For what reason we haven't discovered but , as per
someone's research, animals over 25kg. in body weight were the species which
vanished. Could this be the size which was unable to evade the fog?

When all" the dust" has settled, I expect we will find that it was a total
effect of; toxins, blast, forest fires, tsunamis, mudslides, sunlight reduction,
species lifestyle and vacant niches, rise in CO2 and other gas levels, and
volcanic activity -- which over loaded some species ability to adapt. 

A point was made that the populations more proximate to the impact were more
quickly devastated.  I recall a "fact" that the Meteor Crater impact released
such a thermal blast that "all life" (sic) within a 800 mile diameter was killed
immediately.  The debate goes on today as to what happened as recently as
20-12,000 years ago to the large "African-like" herbivores and carnivores
represented in the La Brea Tar deposits and other fossil sites--A 20 ft tall
rhino, mastodons, mammoths, sloths, horse, camel, atlas lion, saber tooth cat
and etc,--yet the bison , elk, pronghorn, cougar, and jaguar survive today. 
Periodic extinctions are repeated over and over thru the geologic record. Some
species die off and others of similar size and lifestyle survive. (NOTE: human
hunting/expansion and volcanic activity in the southwest have been implicated)

Birds today are known for migratory behaviors which would allow them to exploit
vacated niches.  A vignette example of birds moving into said niches in this
century was the advance of the cattle egret.  In the early 1900s a large flock
was blown by storm from Africa to South America (Brazil). in the intervening
60-80 years they had moved through Central America, The Caribbean, etc. and had
made it as far north as Atlanta, Georgia and San Angelo, Texas. This was not
through migration per se, but yearly population advances into a niche left long
void by the absence of large herbivores which the cattle egret was dependent
upon. Human cattle production and agricultural plowing beat insects out of the
bushes for them and they became reestablished in the Americas. Prior to this
time cattle egrets were only known from Africa.

Vignette evidence of tortoises floating on palm fronds can explain the
occurrence of the tortoises on the relatively young volcanic Galapagos Islands. 
The bottom line here is, given some means of survival thru the initial lean
years, there is a mechanism to explain repopulating of classes, families, and
species into areas where the populations were devastated, including islands and
if the animals were small enough. The repopulation rates were probably faster
then most of us would think and in geological time it was a blink of an
eye--fast enough  for there to be no break in the fossil record for some species!

Regards,
Elton

Phil Bagnall wrote:
> 
> > Hello list....  I still don't buy this nickel (poisoning theory)!
> 
> You cannot escape the fact that nickel is highly toxic and may well have
> contributed to the extinction process.
> 
> >The impact altered the Earth's temperature for many, many years,
> 
> Did it? Some scientists claim it did but there is little reliable evidence.
> Most meteorologists would tell you that, as the thermal pulse passed over
> the oceans, the water boiled releasing huge amounts of vapour into the
> atmosphere. That vapour would not stay there for very long but would have
> rained out, probably bringing most of the dust with it. The atmosphere may
> have stabilised in just a few weeks or months. <snip>
>

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