Re: UTILITY OF CLADE NAMES

[Jonathon Woolf <jwoolf@erinet.com>]

Tetanurae wrote:

> Jonathon Woolf wrote (quoting me):
> << > This is surprising to you?  Did you think that cladist told people they
> had
>  > some magical way of deciphering the relationhsips of organisms?
>
>  Sure looks that way to me.  Look at the messages I got today claiming
>  that cladistics is simply a method of recognizing the existing evolutionary
>  relationships between organisms.  >>
>
> Well obviously that is the goal of cladistics: to decipher the evolutionary
> relationships between organisms.  This is down by analysing characters.
> Anyone who tells you different is either an idiot or a magician.

Ahhh, now that's not the same thing I was hearing earlier.  _That_ description
makes sense.  But claiming that a cladogram simply recognizes the existing
evolutionary relationships, as if the cladogram is unquestionable revealed truth
-- _that_ is magic.

>  <<And maybe we shouldn't keep it.>>
>
> Why should we discard it just because you don't like it?  It was named and
> reviewed, so it sticks.  I dislike most names given to everything but I know I
> can't go around renaming stuff.

No, but you can join me in trying to see that future names make some sort of
sense.

>  <<Likewise the other examples you name --
>  in ceratopsids, it always struck me as illogical to call something that
>  doesn't have either horns or head frill a "ceratopsid."  Ceratopsids are
> _horned_
>  dinosaurs -- and for the sake of simplicity, anything descended from a horned
>  dinosaur, like _Pachyrhinosaurus_.  Even protoceratopsids could be reasonably
> called
>  horned dinosaurs, since the male _Protoceratops_ has an incipient horn on its
>  nose.  But _Psittacosaurus_ isn't a horned dinosaur and shouldn't be placed
> in
>  Ceratopsia.>>
>
> Why?  It has huge jugal horns that come off of a ridge on the postorbital and
> the jugal, a rostral bone and squamosal shelf over the occiput.  That screams
> Ceratopian to me.  Additionally, how horny does a horn have to be to be a
> horn?

_Tyrannosaurus_ has brow horns, and _Ceratosaurus_ has a nose horn.  Does that
make them ceratopsians?  The rostral bone alone is enough to mark 
_Psittacosaurus_
as *related* to ceratopsians, maybe even close to a ceratopsian ancestor, but it
doesn't make _Psittacosaurus_ a ceratopsian any more than a hadrosaur-like bill
makes _Ouranosaurus_ a hadrosaur.

>  <<Why was Ornithopoda expanded to include dinosaurs without birdlike
>  feet?  And who did it?  Some evangelical cladist on a crusade?>>
>
> The truth of the matter is that ornithopod feet don't resemble the feet of
> birds very much, and it was not some evangelical cladist, it was a 19th
> century paleontologist who saw the utility of expanding group names and the
> uselessness of proliferating new names.

Expanding group names doesn't make any sense if the newly included creatures 
don't
have the features that diagnose the group.  I understand there are no definite
characteristics that can be used to reliably separate the land carnivore 
_Mesonyx_
and its close relatives from its aquatic descendants the whales.  Does that mean
_Mesonyx_ is a whale?

>  <<Names have meaning.  Names have power. Anyone who sees the _name_
> Arctometatarsalia is going to automatically conclude that the name relates to
> a feature common to all members of the group,>>
>
> Not necisarily.  They will see it as a stem based clade thatt includes
> Ornithomimus and all animals that share a more recent common ancestor with
> Ornithomimus than with birds and that some members of that group will have
> been characterised by possesing an arctometatarsus.  Hopefully these people
> will have had the foresight to read Holtz 1994, 1995 and 1996 so they would
> understand that.

<shaking head in disbelief>  Before this exchange, I would have sworn that 
nobody
could be this deliberately dense, except maybe creationists and animal rights
activists.   THE NAME ALONE DOES NOT COMMUNICATE THAT DEFINITION.  THE NAME 
ALONE
INDICATES THAT THE MEMBERS OF THE GROUP ALL HAVE THE ARCTOMETATARSUS AS A
SYNAPOMORPHY.  Whatever nonsense and pseudoscientific doubletalk Holtz slipped 
by
the censors in papers published in magazines to which I have no access does not
matter.  What matters is what a non-expert sees when s/he is reading about
dinosaur groups.  And what that person is going to see is a name that implies a
falsehood.


> A name is just a name after all, it doesn't have anything to do with the
> definition, diagnosis or membership.

A bad one doesn't.  A good one does.  Your cavalier attitude is why there are so
damned many bad names in paleo-taxonomy today, and why a lot of other biologists
think paleontologists don't know a damned thing about taxonomy.

-- JSW

PS: This will probably be my last reply to anyone on this topic.  Or any other.
It's increasingly obvious that the resident monks will not permit questioning of
the Scripture of the Holy Clade, and that amateurs are not welcome to express
opinions that dare to  go against the established wisdom.