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Re: Combined answer...



Hi Jura,
     I would emphasize one point Zoe made.  "Exapt" and "exaptation" should
probably be used only in the original more restricted meaning (i.e., an
extension of an original function to other functions over time, whether you
are talking about feathers, genes, or whatever).  In using the term too
broadly, I think you run the risk of being misunderstood and distracting the
reader from the points you are making.
     But I don't think I would have used "extrapolate" either.  I think a
better term would have been the word "extended" (which you used below),
which has a much broader range of meanings than either exapt or extrapolate.
    But I do agree with your main point, that scaliness (at least partial
scaliness) in dinosaurs is a pretty good default position, "unless there is
evidence to the contrary".  However, I wouldn't apply such a default too
rigidly.  Admittedly some cladists do tend to use phylogenetic bracketing
too loosely and they could be putting feathers where they don't belong.  But
there is always room for healthy speculation and debate.  In fact, your
skepticism about dino-fuzz is understandable to a point, but all things
considered, I think it is real (not contamination).  Just my personal
opinion (at the present time anyway), and therefore concentrating my own
skepticism in other directions.
    Skepticism and speculation (in moderation) are indispensable to the
scientific process.  What one scientist considers moderate skepticism or
speculation may seem excessive to another, but such disagreements obviously
come with the territory.  The only major area where I think such
disagreements have become unhealthy and counterproductive is nomenclature
and classification, but that is because it is an inverted bell curve, with
majorities in two opposing camps (and very few of us in the middle ground).
But for the most part, scientific argumentation can be very productive and
even fun (but frankly I sometimes wonder if the BANDits ever lighten up a
little and have much fun in their work).  Life's too short, and if you can't
let loose, speculate, and have some fun once in a while, it wouldn't be
worth all the work and bother.  All things in moderation.
                  Cheers,  Ken Kinman   :-)
*********************************************************

From: archosaur@usa.net
Reply-To: archosaur@usa.net
To: "Zoe Heraklides" <z_heraklides@hotmail.com>
CC: dinosaur@usc.edu
Subject: Re: [Re: [Combined answer: Feathered/scaly theropods: trying to
make the point.]]
Date: 29 Jun 2001 23:15:41 EDT

"Zoe Heraklides" <z_heraklides@hotmail.com> wrote:
>
>
> "Jura" writes:
> >
> >
> >So to rephrase: "All dinosaurs should be considered scaly by default,
> >unless
> >there is evidence to the contrary."
> >
>
>
> I think the crux of the trouble here is that the opinions expressed here
are

> very strong and forceful in their presentation. Yet, the opinions are
based

> on little evidence - and based more or less (mostly "more") on Jura's
> assertions about dinosaurs and the Yixian localitie(s):
> (1) all dinosaurs are the same where skin/integument is concerned, so we
> have no right to picture ANY dinosaurs were feathered unless we can
prove
> they all were.
> (2) all feathred dinosaurs are found in one tiny locality, which were
> susceptibel to some freaky fungal/dendritic phenomonen which look so
much
> like feathers that paleontologists  havebeen fooled into thinking they
are
> feathers.
> (3) if some specimens shows preserved integument than they ALL should.
In
> other words, Yixian mammals should show hair, Yixian ornithopods should
show

> scutes/scales etc. (But preservation was differential according to the
> nature of the intgegument -  just like Solnhofen and Messel and
Santana.)
>
> Assertions 1,2,3 are incorrect. I am not going to accuse "Jura" of being
> uninformed in this discussion/debate. I would say that the strength of
the
> opinions are not matched by Jura's grasp of the topic. To say that he
has
> not aware of any Yixian birds beside Confuciusornis hints at this. There
are

> at least 20 species of bird so far described, and some have been
described
> in major easy-to-get journals (Science, Nature).

+++++++++++++++++++++++

Most of the references to Liaoning that I got came off of the "fuzzy" dino
papers and none were particularly good. _Confusciornis_ was mentioned in
practically all of them, but I never got any good refs for it in the
citations. They either lead to a certain bird book, who's title escapes me,
or
weren't mentioned at all.

_______________________


>
> Also:
> >>Check out
> >>posts regarding dino metabolism, or theropod behaviour and see how
often
> >>maniraptor gets exapted to all theropods and occasionally, all
dinosaurs.
>
> "Exaptation" is an evolutionary term, coined by Gould (I think in the
> 1980's). It means when an existing structure takes on a new (derived)
> function - and that new functiuon may replace the old one. I think your
> usage may not be right. Do you mean "extrapolate?"
>
>
> Regards, Zoe

+++++++++++++++++

Well my definition for exapt simply states it as another way of saying:
"extended"

In other words, maniraptor often gets extended to include all theropods and
occasionally all dinosaurs when talks of feathery integument are concerned.

Jura


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