Re: Strange thoughts on PN - was Re: BAD vs. BADD

[Martin Baeker <martin.baeker@tu-bs.de>]

> Well first of all, I'm pretty sure that all of those examples are actual
> monophyletic groups, so I'm not sure how they serve your arguement.  If you
> are claiming that non-avian dinosaurs are in some way as real or useful a
> group as monophyletic Canidae, then I think you are highlighting the flaw in
> the idea of using arbitrary groups.  Second (this has been mentioned by
> David), but the problem in that statement is "now-adays".  Sure some people
> only work with extant birds, and some only work with one or another group of
> extinct dinosaurs (avian or otherwise) but to name them as separate
> non-phylogenetic groups is to encourage people to use the wrong inference when
> trying to reconstruct missing morphology, soft tissue anatomy, and even
> phylogeny (because it's human tendancy to assume that the characters that
> "unite" the organisms into said group have phylogenetic value).

I think there is one very basic disagreement on what nomenclature is
good for between us: From what you write (here and below),
nomenclature is used mainly by people talking about extinct animals
and trying to reconstruct the history of life. However, biology (or
zoology) is a bit larger than paleontology. For most of zoology, it
would not matter the least whether on single dog species evolved to a
flying monster or whatever, the grouping Canidae would still be useful
99% of the time.

> It only seems like that when there are large gaps created by holes in the
> fossil record.  There is no morphological basis to claim that Jeholornis is
> meaningfully "undinosaurish," yet it's closer to birds than Archaeopteryx.

And there is no morphological basis to claim that microraptor
(assuming it is outside archae+passer) is meaningfully more unbirdish
than archaeopteryx. As Mike Taylor showed in his post, this argument
cuts both ways.


> The record of paleontology is littered with bad or missed interpretations
> because people assumed that "reptillian dinosaurs" wouldn't have air sacs, or
> feathery integument, etc.

And always insisting on "birds are dinosaurs" will give people the
impression that all dinosaurs are birdish, resulting in JP-type
conceptions. Don't know if this is much better.


> > > > Shouldn't there be a clear-cut systematic way to talk about the set 
> "bony fish" without Tetrapodes? Do you really say that this grouping is
> worthless because we know of perhaps a handfull of fossils (from probably more
> than 50000 fish species known all together) that would be difficult to place?
> Isn't it intellectually even more misleading to tell people: No there is no
> such thing as bony fish, unless you
> include humans?<<<
> 
> First of all, why is this useful?  You can still talk about (or study) any
> group you want, regardless of its phylogenetic validity.  No one is preventing
> researchers from doing a review of basal iguanodontians; we're just argueing
> that there is no need for a non-phylogenetic nomencalture.  Such a system
> would be cumbersome (a whole different system to remember!), and I'm yet to
> see why it's useful, outside of shortening a few sentences in
> conversation.

Then, why is any name useful besides of shortening a few
sentences? Let's always say (passer+archae), (iguano+megalo) etc.  

> As for your fish example, I personally find it is more intellectually
> dishonest to refer to a group that places dipnoans, rhipidistians, rhizodonts,
> and stem group tetratpods alongside trout to the exclusion of amphibians,
> rather than to simply say that tetrapods are a type of sarcopterygian fish.

So you do not recognise that a dipnoan looks much more like a trout
than it does like a bird. I think that sharing lots of primitive
characters, although useless in reconstructing a phylogeny, is still a
recognizable feature that is useful.

Martin.

                   Priv.-Doz. Dr. Martin BÃker
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