Re: Hibernating through the K/T?

["Mike Styzen Shelf Expl, 588-4308" <mstyzen@shellus.com>]

If one assumes that the K/T extinctions are an abrupt event I think
more factors than warm/cold, light/dark, food/hungry, have to be
considered.  Several months ago I posted some of my speculation about
this but I think it's time to reiterate, since there is so much arm
waving going on anyway.  OK here goes:
The Cretaceous is the age of chalk (creta = chalk).  Chalk is probably
the dominant lithology for marine Cretaceous rocks.  The major
component of chalk is (you guessed it) calcareous nannofossils. 
nannofossils are the skeletons of minute marine algae.  Today
nannoplankton constitutes probably the most abundant photosynthetic
biomass on earth.  During the Cretaceous it was even more dominant.  In
addition to the obvious contribution of oxygen to the atmosphere,
nannoplankton also removes CO2 from the atmosphere in the form of
calcium carbonate (hence the chalk) this CO2 is more or less
permanently removed from the atmosphere because it is tied up in the
sediment.  nannoplankton also has some other atmospheric tricks too. 
One of them is a chemical (a metabolic by-product) released into the
atmosphere that promotes acid rain.  This tends to dissolve outcropping
carbonate rocks putting more calcium into the system which allows more
calcareous skeletons.  
Anyway, In the late Cretaceous this system was operating big time.  
At the K/T boundary this was abruptly shut off.  Other groups are more
ambiguous but the evedence for the nannos is that it was sudden.  They
made it through, true, but the population crash at the K/T was such
that by the time they recovered in the Paleocene we can't say for sure
in most cases which Cretaceous genera gave rise to the Paleocene
genera.  The sudden removal of just this one group (and I'm sure there
would be more) would have a profound effect on the atmosphere.  
So once again I've killed off the dinosaurs by wiping out some
microorganisms (applause from the micropaleontologists).
Thanks for your attention
Mike 
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|      Michael J. Styzen               Phone: (504) 588-4308            | 
|      Shell Offshore Inc.             Room:  OSS-1808            
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