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Re: Ocean EcoSystems Unexpectedly Stable (fwd)



Bois said: 
> > I wonder what it was that departed as a result of the event that so
> > "emptied the world"?  After all, rudists were gone before,
>
David M. said:
> Is that "still true"?

Bois, emphatically replies:

I think.

> > ammonites had suffered a Cretaceous-long decline.

> A decline throughout the K? Which strange sort of competition or whatever
> could cause that? I mean, the K was longer than the time that has passed
> since! -- In some places ammonites do appear to die out gradually, but in
> others in the vicinity they last to the very end.

http://www.mpt.org/learningworks/teachers/ntti/8-12/extinctwks4.html

This link copies the figure from Officer and Page's The Great Dinosaur
Extinction Controversy.  Data is from Wiedmann 1969 (ref. if needed) and is
unchallenged as far as I know.  If the record represents reality ammonites
were more successful early in K.
Also, in same link, notice inoceramid clam extinction earlier than K/T.  Saw
a paper in recent (Lethiae sp?) journal talking about predation as cause for
their extinction.

>     From the distribution of Maastrichtian elasmosaurids worldwide it may
be
> concluded that, like mosasaurs, elasmosaurids were still widespread and
> diversified during the late(st) Maastrichtian [...]. Even if precise
> stratigraphical extensions are often difficult to obtain for large
> vertebrate remains, the extinction of elasmosaurids at the K/T boundary
thus
> appears to be sudden rather than gradual."

Is this now the accepted view?  Seems just yesterday that they were extinct
before the boundary.