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Re: The extinction of small dinosaurs (long again)




---------- Forwarded message ----------
Date: Sat, 14 Dec 2002 10:50:49 -0000
From: john bois <jbois@starpower.net>
To: John Bois <jbois@umd5.umd.edu>
Subject: Re: The extinction of small dinosaurs (long again) (fwd)

> The good reason is that a) there is no evidence of competition; b) we have
a
> catastrophe, so we _have to expect_ a catastrophic mass extinction _a
priori_.

This is what I mean by rejecting _known_ causes.  We know
competition/predation are in constant operation; we also know they are
difficult or impossible to detect in the fossil record; this, for you, is
apparently enough reason to say they do not play a role in any
particular extinction.  If I said dinosaurs had red blood, you should
probably say "there is no evidence", and then reject the claim.

> > I don't see the distinction: if a new behavior evolves that results in a
> > competitive advantage, that species' range will increase at the expense
of
> > others'.
>
> If their ranges don't already overlap. Border wars between species are
AFAIK
> very rare.

Clearly, today's borders are the result of yesterday's border wars.

> > Only the most radical of proponents of punctuated
> > equilibrium would suggest that _all_ speciation involves catastrophy.
>
> Actually AFAIK nobody does, because punctuated equilibrium is not about
> catastrophes, it's about evolutionary stasis and allopatric speciation.

Eldredge embraces the notion of catastrophic forces clearing the way for
allopatric speciation.  I actually agree with this--where I disagree with
him is that I think catastrophic forces may well stem from the species
themselves.  For example, man clearing the way for pidgeons, crows, and
company to enter the urban niche.  The way was certainly cleared for mammals
after the K/T.  This was a punctuation.  Perhaps musical notation is more
appropriate than language punctuation.  In many species it seemed a
diminuendo--slowly blinking out.

> > If it is true that speciation may be slow or fast--depending on the
> > individual circumstances, my feeling is that as species develop new,
more
> > complex, strategies and behaviors,
>
> Why "more complex"?

More moving parts...more complex neural circuitry for processing more
complex stimuli and responding with more complex physiological/behavioral
skills.

> > The great changes in
> > utilization of ecospace through geological time
>
> What do you mean?

Different species dominate different niches over time.  Once upon a time
the only vertebrates on land were amphibs--->then reptiles---> and so
on.