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Re: Placental takeover: final comment.




On Tue, 29 May 2001, David Marjanovic wrote:

> > They later make a plea: "the most pressing need today is for new and
> > better paleontological _data_, derived from as yet unknown parts of the
> > fossil record..."
> 
> Of course. I'm not going to, say, publish anything on this. But I think the
> decimation of NA metatherians at the K-T does not contradict the impact
> theory (I think theory rather than hypothesis has become suitable), and I
> think it is not total dilletantism to post this here.

No, it doesn't contradict the hypothesis.  But the word "theory" is
inappropriate.  The fact of a bolide doesn't generate a theory of species
survival.  A theory explains phenomena.  The bolide isn't a theory
because it does not do a good job of explaining.  Natural selection is a
good theory because it has broad explanatory power.  Plate techtonics,
ditto.  Indeed, there are no surviving alternate hypotheses for how
continents came to be where they are.  This is _not_ true for speciation
across the K/T!  Respected scientists paw over the data and scratch their
heads.  But saying the case is closed gives people, funders, etc., the
impression that nothing more needs to be known.  I mean, if you come to me
for money to dig up more fossils at the K/T, I say: "Why bother if you
already know what happened."
A better way of approaching it is to say the speciation _may_ be explained
by the bolide.  Let's do some more research to find out.
I know you agree with the research part.  But what's the point in asking a
question if you already have your answer?

> > And here I want to voice my discontent with the scientific complacency of
> > some on this list.  To claim one knows what happened 65 mya--i.e., that
> > placentals and marsupials were strictly casualties of an extinction
> > "event" and that ecological forces were irrelevant--is to claim something
> > that cannot be known.
> 
> What may not be known now, but what can be known. With ever better data, of
> course. So far, I'll stick to what the present data suggest to me

Right.  Everyone tries to interpret data to their satisfaction.  But they
shouldn't then tell everybody: "This is what actually happened."  I fear
if you are now upgrading your hypothesis to a theory, that this is what
you are doing.

 > > But when you
> > say you already know what caused species distribution at this time, you
> > are ineffect saying we don't need more data.
> 
> Mmm... no. Never in science are more data useless.

But there are always choices about which research is funded. No one is
going to fund an inquiry into whether the Earth is spherical.

> > would have...blah, blah, and firestorms would have...blah, blah.  I mean,
> > it was just yesterday that everyone was warning everyone else not to make
> > up stories without having direct evidence.
> 
> I haven't read the book :.-( ; however, there is evidence for global
> firestorms -- the boundary layer contains lots of soot. Tsunami deposits
> from the K-T are also known,

As far as I know, none of these things appear in the sediment of this
study.