Re: K/T boundary

[Peter Sheehan <sheehan@csd4.csd.uwm.edu>]

On Thu, 17 Nov 1994, Mike Styzen Shelf Expl, 588-4308 wrote:

> Hi, 
> I'm a calcareous nannofossil paleontologist so I spend lots of time
> thinking about those little rascals.  For those of you who are
> unfamiliar with nannos, let me tell you some background. Calcareous
> nannoplankton is tiny (usually just a few microns) algae that floats
> around in clouds of untold billions in the oceans.  The tiny skelital
> remains of these organisms is the major constituent of chalk.  The
> Cretaceous is the age of the nannofossil;  chalk everywhere.  Right up
> to the end of the Cretaceous nannos were cranking along making many
> tons of carbon dioxide into calcium carbonate (which sinks effectivly
> removing it from the system) every day.  It is pretty well established
> that at the end of the Cretaceous just about all the calcareous
> nannoplankton crashed at once.  I've seen very little in print about
> the effect of suddenly turning off this giant CO2 removal machine on
> the rest of the environment.  But it seems to me that this alone could
> set off an ecological shockwave that would greatly contribute to the
> demise of lots of other creatures both marine and terrestrial.    
> 
> =========================================================================
>       Michael J. Styzen                   Phone:  (504) 588-4308
>       Shell Offshore Inc.                 Room:   OSS-2920           
>       P.O. Box 61933                      E-mail: mstyzen@shell.com
>                      
>       New Orleans LA  70161                
> =========================================================================
> 
Not to mention that food for zooplankton disappeared.  And it needs to be 
emphasized that the crash was precisely at the impact clay layer.  

Mike Arthur and associates did pioneering work on geochemical isotopes that 
indicate cessation of primary production in the oceans (Cretaceous 
Research 1987  v. 8:43-54.)  This is another line of confirmatory 
information.  

As I have suggested before.  The Signor-Lipps effect suggests that the 
most abundant organisms, ie nanofossils, should have a record with
almost no gradual decline.  Progressively less common forms should have a 
record with an apparent, but unreal gradual decline.  For example, 
planktonic forams are very abundant and they have a very slight 
Signor-Lipps decline.  Dinosaurs, with a very scanty record, should 
appear to have a much longer apparent
 but unreal gradual decline .