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

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

> Actually, my schooling was in zoology, not geology, and I follow the
> neontological literature as a matter of course; I suspect that most of the
> phylogenetic nomenclature guys (and gals) here are interested in extant animal
> groups.  Again canidae is a monophyletic group, whether it contains flying
> monsters or not.  Please provide an example of how a paraphyletic grouping is
> of more use to neontologists than a monophyletic grouping is.  Otherwise, the
> distinction you are trying to draw between disciplines doesn't appear to exist
> (in this case, anyways).


After thinking about your (and other) posts for a while, I think I
understand a bit better part of what bothers me.

Just imagine the following story (it's another version of the same argument I'm 
always making):

You just submitted your new, groundbreaking work on, say, triceratops
to the 1st World congress on dinosaurs. It is assigned to
session number 2 of no less than 21 sessions. Wow, you think, that's
going to be a largo dino-conference. Later that day you talk to your
friend, whose talk on T rex feeding behaviour is *also* assigned to
session 2. Strange, isn't it? After getting hold of the conference
program, you find out, to your surprise, that this is really a
conference on all dinosaurs - all the other sessions are on dinosaurs
as hawks, sparrows, goose, ostriches, teratorns, moas, etc.


No matter how strong the arguments for birds being dinosaurs are (and
they are obviously overwhelming, there is no need to argue on that),
whenever you say or hear "dinosaur", I'm quite sure your first thought
is *not* of a bird.


But perhaps (as I keep saying, I have not fixed my mind on all this
and try to form an opinion) when we use the name of a monophyletic and
well-recognised group, it is always clear that the focus is on the
basalmost members of the group; if it weren't we would use the
next-higher clade (birds, instead of dinosaurs).  Perhaps this is
intuitively obvious to those of you who strongly argue against naming
paraphyletic taxa, but then people on the list (or elsewhere) should
stop the "but-birds-are-dinos"-nitpicking that seems almost inevitable
now whenever someone says something like "dinosaurs are extinct" etc.


> 
> > > > 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.<<<
> 
> Huh?  How does it cut both ways?  I'm happy to follow that line of thought,
> because there is no obvious way in which other dromaeosaurs, trodontids, or
> oviraptors are significantly less birdish than Microraptor.  Congrats, you've
> just included all of maniraptora (including therizinosaurs, whose derived
> members don't look terribly birdish, but whose basal members do), and we could
> keep running that mind experiement all the way to the bottom of the eukarotic
> line, at which point the world would be very, very full of birds.
> 

It cuts both ways because defining birds as archae+passer is also
completely arbitrary. There was a critter somewhere that was very
similar to archae, but will fall outside of birds. So if you ask
"Where do you draw the border between dinos and birds?" the answer is
simply: At the same place you do (i.e., draw the border between avian
and non-avian dinos). If dinos includes birds, then the set dinos
without birds is *no more or less* arbitrary than the set dinos and
the set birds are.

So, to turn your argument from above around: Why not 
birds=passer+microraptor or
birds=passer+dromaeos etc.
It's just an accident of history - we knew about archie befor
microraptor, it is all completely arbirary.

> > > 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.<<
> 
> What kind of JP-like conceptions are you speaking of?  All dinosaurs ARE
> birdish compared to less derived archosaurs, and especially compared to
> squamates.  Obviously the further away you get from birds (but within
> dinosauria) the less birdish they tend to be, but still, compared to
> non-dinosaurian diapsids, even an upright, stiff-legged fast-growing hard
> eggshell laying Maiasaura is a lot more bird than an iguana is.

Probably, but if you think of JP, what you see there is rather dinos
as "superbirds" (bigger, smarter, faster) than as something *between*
less derived archosaurs and birds. (Probably, that's partly to make
better theme park monsters and partly due to the standard logical
fallacy: if A is B then B is A.)


> > > Then, why is any name useful besides of shortening a few sentences? 
> Let's always say (passer+archae), (iguano+megalo) etc.<<
> 
> I'm sorry, I guess I wasn't clear; I'm not saying that naming itself is a
> useless convention, I'm saying that it appears that the confusion and extra
> work required to create, learn, and maintain a separate non-phylogenetic
> nomenclatural system waaaaay outways any obvious benefit for having said
> system.  Especially becaue we have yet to be shown a single situation in which
> a non-phylogenetic system is in fact more useful.

But considering the immense bother people take to think about naming
clades, arguing how to do it, thinking about a new nomenclature -
couldn't we completely get rid of it and only name species in the
future in this simple way?


> 
> > > > 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.<<<
> 
> As has been pointed out, it's better to compare a dipnoan to Acanthostega than
> a bird, but even with a bird, it depends on what you are looking at.  If you
> mean that dipnoans and osteichthys both lack feathers, than sure.  But what if
> you are looking at mtDNA?  It's not just morphology that's of interest to
> neontologists.  What about brain organization?  Habitat? (should penguins be
> more closely related to fish than other birds?) Dermal color?  Respiration?

So, a dipnoan is closer in brain organisation, habitat, color and
respiration to a bird? Obviously I misunderstand what you mean here...

Once again, thanks to everyone involved for helping me understand this
better - however, I will not be able to participate for a while in
this discussion, as I'm on my way to a vacation (but if you answer me,
I'll catch up when I'm back).

Cheers,

Martin.

                   Priv.-Doz. Dr. Martin BÃker
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