Combined answer 1: cladistics

["David Marjanovic" <david.marjanovic@gmx.at>]

> >:-) The hypothesis is not unscientific anymore. But before the advent of
> >cladistics -- the method to make phylogenetic hypotheses and to test how
> >well they fit the totality of the data -- it was. "Unscientific" doesn't
> >mean "wrong". It just means "if it's wrong, we can't find that out with
> >certainty".
>
> Nor was it unscientific when it was presented.

I think it was, and Mickey has explained why.

> Occam's Razor is one thing, but naive adherence to parsimony is another.
It
> is a central tenet of cladistic analysis that convergence, paralellisms,
and
> reversals are very rare

Oh no. Not at all. IT is a central tenet of cladistic analysis using
parsimony that homoplasies are a bit rarer than synapomorphies -- just a
bit.

> Indeed within Aves we see astonishing convergences, time and again.

This means that we should be very careful before giving a character high
weight. It also means that, if we get a cladogram of good size but a high
consistency index, we have to assume that there's a bias in the data set (e.
g. the CIs of Sereno's cladograms are 2 and 3 times those of other people's
cladograms, implying that -- as he AFAIK says anyway -- he omits characters
which he thinks are "prone to convergence").

> To claim for instance that anything which calls for convergence
> and so on is ad hoc fails to distinguish between ad hoc hypotheses, and
> auxiliary hypotheses.

:-) May well be, because I've never seen the latter term. -- See above, we
don't expect to need zero ad hoc assumptions, or anywhere near that few. We
just expect that we need as few as possible.

> While we almost all agree that shared derived characters ought to be used,
> this idea that cladistic analysis in the solitary scientific method of
> phylogenetic reconstruction, with a monopoloy on accuracy and objectivity,
> is simply farcical.

Obviously it doesn't have a monopoly on accuracy -- or if it does, we can't
find that out, because to do so we'd have to compare cladograms to The True
Tree. But... what other scientific methods are there for phylogenetic
reconstruction? I know none.

----- Original Message -----
From: "John Pourtless" <vindexurvogel@hotmail.com>
Sent: Saturday, January 31, 2004 8:13 PM

> We are all well aware of the dissolution of Thecodontia
> in the past 20 years or so.

Great -- my point was that apparently the BAND isn't aware of it.

> > > Indeed, revisions to the theropod origin of birds have
> > > arisen via the challenges presented to that hypothesis,
> >
> >I'm having a little blackout... could you remind me of such a revision?
>
> I was under the impression that the criticism that the semilunate carpal
> element was not homologous between theropods and birds, largely prompted a
> revision of Ostrom's interpretation of this structure, display that it is
in
> fact a distal carpal in both theropods and birds, therefore rendering them
> homologous.

Could be, though I don't know the exact history of these events.

> >That Feduccia and Martin and Olson are just too ignorant of nonavian
> >dinosaurs to know the difference between hollow rhetoric and real
science,

when it concerns nonavian dinosaurs, I forgot to add,

> >you mean.