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Re: Steadman's review of Mesozoic Birds






From: "David Marjanovic" <david.marjanovic@gmx.at>
Reply-To: david.marjanovic@gmx.at
To: "DML" <dinosaur@usc.edu>
Subject: Re: Steadman's review of Mesozoic Birds
Date: Fri, 30 Jan 2004 19:09:43 +0100

> >The debate over whether the magnetite contained
> >in the Martian meteorite is indeed biogenic
> >(and therefore indicative of past or present life on the Red Planet)

"Therefore"? We'd still have to rule out contamination -- colonization of
the meteorite by bacteria while it was lying around on the Antarctic ice.
IMHO that's quite likely what happened.

> >Molecular systematics actually employ cladistic methodology.

That part that isn't phenetics instead (namely the distance methods --
DNA-DNA hybridization and neighbor-joining. These techniques are getting
rare, though.).

> but it is equally astonishing to see the very idea that the
> theropod hypothesis is incorrect, relegated to the realm of
> quasi-creationist pseudoscience, and with it the denigration
> of an entire discipline (ornithological systematics).

Feduccia likes to play "the paleontologists" against "the ornithologists".
Fact is, he's rather isolated among ornithologists as well.

What is relegated to the realm of pseudoscience is not "the very idea that
the theropod hypothesis is incorrect". It is the way Feduccia keeps up his
hypothesis. For example, it is plain obvious from all of his writings that
he has no good working knowledge about dinosaurs. As late as 1996 (has this
been changed in the 1999 edition of his book?), he wrote that the
predator-prey ratios of the Late Cretaceous of North America were deeply
flawed because hadrosaurs lived in the water, not on land where the
tyrannosaurs lived. It made me cringe. And "only four dinosaurs" have a
semilunate carpal, and none has "bird teeth", and so on... oops, sorry, the
teeth are meanwhile completely, totally irrelevant, because MANIAC.

> The data on the possible lack of homology between the theropod manus and
> bird manus (which I do not think is the case), 'is' real and valid,

I think the hypothesis that birds have the fingers 2, 3 and 4 is less
parsimonious than the alternative, and I'm arguing from embryology,
including photos that Feduccia published. I'll put this on a website...
hopefully sometime next month.

> philosophy of how to represent phylogeny.

Cladistics is not a philosophy of how to represent phylogeny, but of how to
find it out. And the only philosophical part in it is Occam's Razor. :-)

> For instance, to dismiss an analysis for the solitary
> reason that it does not produce a PAUP generated
> cladogram, makes no sense to me.

To me it does (as long as one counts McClade, NONA, PHYLIP, Hennig86 and
whatnot, too :-) ) -- because cladograms are testable, while "yeah, there
must have been some strange little arboreal archosauromorph in the Triassic,
and every single of the hundreds of primary homologies between birds and
[other] dinos must, must, must be convergence" is _not_. (And therefore not
scientific. Do I realize that hereby I say that the phylogenies drawn by
Romer, von Huene, and all the other grand old people are unscientific, too?
Yes. Not necessarily wrong, but unscientific.)


> Systematists these days seem to forget that much good
> science was done prior to the advent of the Hennigian system,

but the phylogenetics was largely a just-so-story affair.

> And as for molecular systematics for resolving the evolution of birds...we
> who find it to be anything but the universal panacea for that riddle are,
it
> seems, in the minority.


Look e. g. at the discussion about the sistergroup of whales (hippos alone,
or artiodactyls in total?), and you'll see that this isn't the case.
Molecular evidence is evidence, no more and no less.



Cladistics is a tool--it is a method for generating hypotheses--it is 'not' an inerrant formula for producing flawless phylogenies. To reject a hypothesis for the singular reaosn that it fails to produce a cladogram is as flawed as circular logic. Need we remind ourselves that the very hypothesis we are by and large united in defense of, the theropod origin of birds, did not spring forth from cladistics, and by your own criterion would be rendered unscientific? To equate cladistics to the one true way of representing phylogeny, the only scientific method for the determination of evolutionary relationships, is to effectively elevate this tool to blind dogma, precisely as its critics have argued. Ironically enough, this standpoint is as flawed as those which entirely reject the utility of cladistics. I find it of lasting poignance that John Ostrom vigorously criticized cladistics.

JGK

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