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Date: Tue, 15 Jun 2004 22:30:01 +0200
From: David Marjanovic <david.marjanovic@gmx.at>
To: DML <dinosaur@usc.edu>
Cc: PML <phylocode@ouvaxa.cats.ohiou.edu>, "Jonathan R. Wagner" <jonathan.r.wagner@mail.utexas.edu>
Subject: Re: Pan-clades, good or bad?
Let's see if I can make one big combined answer on this... I hope it's not
too big.
----- Original Message -----
From: "Mickey Mortimer" <Mickey_Mortimer111@msn.com>
Sent: Tuesday, June 01, 2004 7:40 PM
Subject: Pan-clades, good or bad?
> Tim Williams wrote-
>
> > " "Pansphenisciformes" is used here as a name for all taxa more closely
> > related to extant penguins than to any other extant avian taxa.
> > "Sphenisciformes" is suggested as a name for all parts of this lineage
> > with a loss of aerial flight homologous with that of extant penguins.
> > These definitions are deliberately not formalized pending recommendation
> > of the PhyloCode regarding the proposed use of "pan" as a prefix in all
> > stem clade names (Gauthier and de Queiroz, 2001 )
>
> What are others' opinions on using the Pan- prefix for all stem-based
> clades? Personally, I find it terribly monotonous.
The idea is different. Read the abstracts by de Queiroz & Gauthier, Gauthier
et al. and Clarke et al. in the IPNM abstract booklet
http://www.ohiou.edu/phylocode/IPNM.pdf. My opinion is obvious from the rest
of this e-mail...
----- Original Message -----
From: "Christopher Taylor" <ck.taylor@auckland.ac.nz>
Sent: Tuesday, June 01, 2004 11:26 PM
> Unnecessary, overly restrictive, and potentially misleading -
> Panarthropoda is at least one example I can think of of a clade
> that is not merely the stem group of its root-taxon (Panarthropoda
> contains Onychophora and Tardigrada, as well as Arthropoda).
> In this case, the use of the prefix 'Pan-' reflects that the other
> taxa were previously included in a taxon 'Arthropoda' that had a wider
> interpretation than it does currently, and I would have thought that this
> was a more appropriate use of this prefix.
Thank you for alerting me to this example! Yes, the intention behind
Panarthropoda seems to have been "everything that has ever been called
Arthropoda". (Like Holotheria, which includes everything ever called
Theria -- starting with *Kuehneotherium*, which is outside the mammalian
crown group as well as one or two other node-based definitions of Mammalia.)
Well. Whether Panarthropoda _is_ an example depends on whether we consider
Onychophora and Tardigrada well-known names. The idea seems to be to define
all well-known names that contain living representatives as crown-groups and
to then make Pan-clade names based on them.
----- Original Message -----
From: "T. Michael Keesey" <mightyodinn@yahoo.com>
Sent: Wednesday, June 02, 2004 5:03 AM
> --- Mickey Mortimer <Mickey_Mortimer111@msn.com> wrote:
> > [...]
> >
> > What are others' opinions on using the Pan- prefix for all stem-based
> > clades? Personally, I find it terribly monotonous.
>
> Not only that, but, if you apply their philosophy to our species and its
> closest extant relatives, you'd get something like:
>
> +--Pangorilla (crown-modified stem)
> | `--Gorilla (crown)
> | |--Gorilla gorilla
> | `--Gorilla beringei
> `--Panhomopan (crown-modified stem)
> `--Homopan (crown)
> |--Panhomo (crown-modified stem)
> | `--Homo sapiens
> `--Panpan (crown-modified stem)
> `--Pan (crown)
> |--Pan troglodytes
> `--Pan paniscus
I see no reason to think a name like *Homopan* would be coined. *Panpan*, on
the other hand, seems to be mandated by the Pan- proposal.
----- Original Message -----
From: "Jaime A. Headden" <qilongia@yahoo.com>
Sent: Wednesday, June 02, 2004 5:09 PM
> My short answer on the use and utility of pan-stems, as de Queiroz and
> Gauthier use them:
>
> Pan-stems have a highly functional use in that they are definitions for
> clades that include ALL possible members, extant or otherwise, that belong
> on the stem to the crown-clade. This makes them rather important in some
> cases, as they become the most useful taxa in a system of living
> organisms. [Joyce, Parham,] and Gauthier has a publication in press
> ascribing this theory to turtles with some rather ... upsetting ...
> philosophies endorsed, so when that paper is published, we can all see
> what is in fact hitting the final print (maybe Ragnarok will NOT occur).
(For those not in the know, Ragnarök is the Norse end of the world by fire.)
> Pan-stems were argued for a long time back. For all extant Tetrapoda,
> pan-stems were used for the most inclusive clades including the largest
> crown-groups exclusive of one another, as in say traditional groups of
> "amphibians," "mammals," "turtles," "lacertilians," "crocs," and "birds."
> Each of these gets a pan-stem, usually applied to the traditional name for
> the crown: Panlissamphibia, Panmammalia, Pantestudines/Pantestudinata,
> Panlacertilia, Pancrocodylia, and Panaves.
What would be *Panlissamphibia* here will likely get the name
*Amphibia*; see the abstracts by Laurin and Anderson in
http://www.ohiou.edu/phylocode/IPNM.pdf.
> We've already seen the last in
> print in the Ostrom Symposium volume from Yale a few years back. EACH
> grouping of pan-stems gets it's own pan-stem: Panarchosauria, Panreptilia,
> Pandiapsida, Panamniota, and Pantetrapoda. In some cases, the alternate
> arrangements get their own potential pan-stems, such as a turtle+mammal
> clade, or a "turtle as reptile" clade, or even a turtle+lacertilian clade.
> [Joyce] et al. will be offering multiple pan-stems for the various
> possible placements of some living turtles to one another. Now imagine
> doing that with snakes ... or birds.
>
> The MAJOR problem I have with pan-stems is that these are very important
> historical points in the history of things DYING and SURVIVING (we honor
> what lives today with names, and ignore the various fossils species
> outside these relatively few nodes -- they are usually IN the stem, or in
> another sister or more inclusive stem, under this philosophy, as is
> generally applied in the node-stem triplet application to cladistics).
> They have _little_ utility in recognizing diversification, new features or
> populations, or essentially record any information about the speciation
> and the arrangement of species or populations save those that live today.
I agree.
> There is a warning in [Joyce] et al. that I hope will be fixed before
> it hits critical mass and triggers Ragnarok (yes, yes, it's an extreme)
> (and it's the major reason I dislike the quick application of the
> PhyloCode): depending on getting the name defined first, it is possible to
> define a new, younger name that will immediate gain precedence over any
> older, synonym those authors chose not to define. [Joyce] et al.. do
> just this in arguing that if the content proves identical between the
> pan-stem and the included next most-inclusive node or stem, the pan-stem
> should have priority ... it will, after all, be defined first and makes
> "more" sense as it is THE most inclusive stem of that included clade.
> PhyloCode offers that if someone defines a name with a definition that is
> in conflict with historical usage, such as the point brought up between
> Mickey and myself recently regarding Hesperornithes and
> Hesperornithiformes, then history _be damned_, as well as constancy
> through the literature. Out goes history and precedent, because PhyloCode
> will seek to "reset" priority. Those who disagree with PhyloCode will
> continue to use systems and nomenclature that others following the Code
> will not, and neither would be technically _wrong_. The pan-stem
> application above that of another stem (say, "Pansynapsida" has priority
> over "Synapsida" if someone publishes the definition first for the same
> content) is the best example of this.
For this example, I'd say *Panmammalia* would have priority over both,
because Mammalia is much more widely known & used than Synapsida.
(Personally I say name that clade *Theropsida* in the first place...
node-stem triplet *Amniota*, *Theropsida*, *Sauropsida*... first proposed, I
think, in 1930, and in limited use ever since.)
I really don't like implied names. The Pan- business could become
like today's confusing rule of the ICZN that says if one names a family
(-idae), one automatically names a superfamily (-oidea), subfamily (-inae)
and tribe (-ini), and perhaps (I don't know) a subtribe (-ina), and when 100
years later someone uses any of those implied names for the first time, they
have to be ascribed to the author of the family.
----- Original Message -----
From: "Tim Williams" <twilliams_alpha@hotmail.com>
Sent: Wednesday, June 02, 2004 6:43 PM
Subject: Penguins (was Re: "Dinosaurs Died Within Hours After Asteroid Hit
Earth..." )
> As Jaime alluded to, the proposed definition of Sphenisciformes ("loss of
> aerial flight homologous with that of extant penguins") is fraught with
> problems. Even if we had these transitional taxa, would we be able to pin
> down exactly when aerial flight was lost? It's like Gauthier and de
> Queiroz's proposed definition of Avialae ("having wings associated with
> powered flight") except in reverse. The same problem applies: defining a
> clade based on a behavior that is unpreservable and based entirely on
> ecomorphological inference.
Gauthier (pers. comm.) points out -- correctly -- that there will always be
fossils too fragmentary to assign to an apomorphy-based clade, or even to a
node- or stem-based one if they're too incomplete to tell their precise
place on the tree. But I still think that we should strive to make as many
organisms as possible as classifiable as possible. Therefore I'm against
using badly preservable apomorphies for defining well-known clade names
(...such as *Aves*).
----- Original Message -----
From: "Christopher Taylor" <ck.taylor@auckland.ac.nz>
Sent: Thursday, June 03, 2004 12:50 AM
Subject: Re: Crown groups
> On 3/6/04 10:29 am, "Tim Williams" <twilliams_alpha@hotmail.com> wrote:
>
> > Jaime Headden wrote:
> >
> >> De Queiroz et al. will be offering multiple pan-stems for the various
> >> possible placements of some living turtles to one another. Now imagine
> >> doing that with snakes ... or birds.
> >
> > Or insects. Egad!
>
> Especially when the name "Panorthoptera" is already in use for a clade
> including not just the total stem group of Orthoptera, but also Phasmidea
> (Hmmm.... Panpanorthoptera?).
Whoops.
> Also, try saying 'Panmantodea' three times fast.
?
> On the upside, it allows great scope for entomological doggerel -
> 'Panisoptera' rhymes with 'Anisoptera' :).
:-)
> >> The MAJOR problem I have with pan-stems is that these are very
> >> important historical points in the history of things DYING and
> >> SURVIVING [...] [see above]
> >
> > I think I know what you're driving at here, and it's an excellent point.
> > The very concept of a "crown group" is anthropocentric: it is anchored
> > in those taxa that happen to have survived into the Holocene. Thus,
> > these are the critters that we can actually clap eyes on because
> > they are the survivors.
> >
> > There is no fundamental phylogenetic principle behind the "crown group"
> > concept; it is wholly taxonomic. For example, we are all familiar with
> > the crown group Aves. But if an alien taxonomist landed on Earth 66
> > MYA,
> > the crown group would be Dinosauria (or Xzylbtttfggzzt in his language).
> > Similarly, Neosauropoda would be a crown group prior to the K/T
> > boundary, but not the long-extinct Prosauropoda.
>
> [...] True, there is no ultimate reason for
> taking our time as more significant than any other, but it happens to be
> the one we're in, and all our studies are influenced by that fact.
> Also, crown groups are significant in that characters that cannot be
> established from fossils (behaviour, biochemistry,...) can only be
> definitely assigned to crown groups. This is, after all, the main argument
> behind restricting familiar terms to crown groups
While, in fact, it's just an argument for _naming_ crown groups at all. :-)
> (it avoids the inherent possibility for error in common statements
> such as 'all mammals produce milk').
While it doesn't avoid the inherent possibility for error in other common
statements such as "mammals give birth to live young" or "marsupials are
characterised by their marsupial bones". Or -- a real example -- "poison
spurs are a synapomorphy of Monotremata". (They are at least one of the
crown group of Mammalia, with at least one secondary loss; for monotremes
poison spurs are plesiomorphic.)
> Just for the record, I'm not convinced by the case for crown-clade
> restriction - neontologists aren't really assuming such statements are
> applicalble to extinct stem taxa, they're merely ignoring them as the
> impossiblity of knowing about them makes them irrelevant to their studies.
I agree.
----- Original Message -----
From: "Jonathan R. Wagner" <jonathan.r.wagner@mail.utexas.edu>
Sent: Friday, June 04, 2004 12:44 AM
Subject: Re: Crown groups
> Christopher Taylor wrote:
> > Just for the record, I'm not convinced by the case for crown-clade
> > restriction - neontologists aren't really assuming such statements are
> > applicable to extinct stem taxa, they're merely ignoring them as the
> > impossibility of knowing about them makes them irrelevant to their
> > studies.
>
> You are quite correct that they often ignore extinct taxa rather than
> deliberately using crown clade definitions. However, they do associate
> taxon names with particular attributes on a REGULAR basis, e.g.,
> "Mammalia is diagnosed by hair," "the crocodilians have a semi-erect
> gait," "Aves is the sister-group to Crocodilia (sic)."
Of course, "Aves is the sister-group to Crocodylia" becomes even wronger, if
I may write that, when those terms are restricted to their crown-groups.
BTW... about half of all occurrences of *Crocodylia* in the IPNM abstract
booklet http://www.ohiou.edu/phylocode/IPNM.pdf are spelled *Crocodilia*.
Perhaps this spelling will win? I'd like this, because it's etymologically
correct, and people seemingly never get used to the y version anyway.
> The point is, do you want taxonomy to
> agree with the statements of 99+ percent of natural scientists,
(Are there really so many zoologists and botanists out there? What about
"80+ %"?)
> or will paleontology always be the whiney little know-it-all who has to
> correct the teacher every time ("but some members of Aves had teeth...")?
Yes, in any case. :-) Without paleontology, we'd probably think the absence
of the cleithrum and tens of other bones were synapomorphies of Amniota --
while such features evolved several times independently. If we extend this
game-spoiling behavior to nomenclature or not would make rather little
difference.
> I will readily admit that, as a justification for an action,
> preferring crown clade definitions is ultimately quite weak. But can
> you find a more objective place on the great Bulletin Board of Life to
> thumbtack those names? I'll save you the trouble of answering: you can't.
Oh, I agree. But when we already have to find a subjective place, let's take
one that some sort of public is used to. For example, everyone with _some_
interest in fossils and/or evolution, as well as _every_ biology schoolbook
author*, knows there are Mesozoic birds, but no remotely widely known
Mesozoic bird fossil belongs to the crown-group.
Sure, there are more neontologists than paleontologists. But the
buck doesn't stop there! The PhyloCode will _in any case_ necessitate the
rewriting of schoolbooks as well as museum exhibits. Where we can, I think
we should help to make this transition easy.
* Now that "we're not in Kansas anymore"...
> The problem is
> that, due to the wonders of what Chris Brochu once called the Linnean
> "floating point definition," it is often difficult to establish
> unequivocally EITHER what is the original intent OR the "current use" of a
> taxon name, and it is usually impossible to reconcile BOTH such that
> everyone will be satisfied with the application of the name.
:-) Well said. I disagree, though, with the notion that the "current use"
were so difficult to establish that we should rather ignore it altogether.
We should take a look at what it is about which the point of the
"definition" floats. It's usually a certain group of taxa, "defined" not
quite by its membership, but rather by the essence of the Linnaean system --
essentialism. A concept, an imagination, in other words. As seen from the
varying uses and non-uses of "Aves" "Mammalia", "Dinosauria",
"Tetrapoda"/"Amphibia", "Amniota"/"Reptilia" and more, it seems that many
such concepts are quite stable, so stable that they could be circumscribed
by an ordinary node-, stem- or apomorphy-based definition.
> By opting to recognize crown clades, we apply the
> only available, remotely objective criterion for separating things
> that "look like X but aren't" from things that "are X."
So remotely objective that what I write above applies...
> Sure, the line that criterion dictates is a product of historical
> contingency, and is almost always NOT what your average neontologist
> associates with the term. I've seen some very savvy phylogeneticists slip
> on this sort of thing quite regularly, including a frog systematist who
> insisted that we should use Amphibia instead of Lissamphibia (I agree),
> and apply it to the crown clade, then turned around two lectures later and
> called Eryops an "amphibian."
(Which is why I support Michel Laurin's definition of *Amphibia*, which will
be formally proposed at the meeting in Paris. Being stem-based, it will
ensure that many Paleozoic traditional "amphibians" will remain ones.)
> I think that paleontologists, by applying the name outside the crown
> clade, have confused the neontologists, and they seem
> to be just trying to keep up.
I think that for a long time paleontologists were neontologists who had a
few fossils in their collections in addition to the taxiderms...
> So, yeah, crown clades are a *little* more objective, but please no
> one. However, they do have the added benefit that they correspond to what
> neontologists WRITE (as opposed to what they think they mean, if they have
> even considered the question at all).
See above; this is true in some cases, but by far not all.
> Crown clades DO provide an external
> reference, albeit an arbitrary one, for communication across disciplines.
> If Tim Rowe says he has a mammal, I can make certain predictions
> about the animal: it will have limbs, it will have glandular skin, etc.
> In fact, I can pick up any mammalogy textbook and tell you a whole
> bunch about it. However, if Spencer Lucas says he has a mammal,
> the most I know is that he has a non-pelycosaurian-grade synapsid
> ("panmammal"), and that is only if I know him and his work!
Actually, this is just an argument for implementing the PhyloCode at all.
Once the definition of *Mammalia* is fixed, you will know what any and every
biologist means when they say they have a mammal.
> A neontologist might very well assume he means a
> crown-clade mammal and start mentally applying their characteristics
> to the animal in question. Is this communication?
No.
But perhaps I should mention the general fact that all such
applications are only valid if a certain phylogeny is presupposed anyway.
Besides, I could be nasty and point out that many a popular book has
said "*Morganucodon* was a mammal because it gave birth to live young" --
which it certainly didn't, being outside the crown-group. Once again, people
had forgotten the monotremes. You've always despised popular books? It's
surprisingly common to forget basal representatives of the crown-group _even
in the primary literature_: Many zoologists have grouped the flatworms
(Plathelminthes) and the ribbon-worms (Nemertini/Nemertea/...) as
"Parenchymia" because the most derived and therefore biggest representatives
of both have an unspecialized filling tissue called parenchyma between their
skin and gut. All other (living!) members of both clades lack it.
> Ultimately, neontologists study extant things, and they often make
> sweeping pronouncements about the characteristics of groups, *effectively*
> applying a crown-clade definition (because they fail to check with
> paleontologists first, those fools! ;).
This argument works both ways. "Only birds have feathers"... "Only mammals
have a phalangeal formula of 2-3-3-3-3"... "only monotremes have those
poison spurs"...
> And neontologists outnumber paleontologists by a substantial margin.
> It makes sense to adopt a strategy that maximizes the number of
> people *already* using your system correctly,
> minimizing the need for constant, irritating corrections. The ones who
> suffer are the paleontologists, who, in the end, are probably the only
> ones sensitive to the issue in the first place. I, for one, am willing to
> "take on for the team."
I think we'd just shift the confusion to a somewhat different place.
----- Original Message -----
From: "Jonathan R. Wagner" <jonathan.r.wagner@mail.utexas.edu>
Sent: Friday, June 04, 2004 11:48 PM
Subject: Re: Crown groups
> > However, I was questioning the wisdom of
> > constructing naming conventions around these crown clades, especially
> > the use of the Pan- prefix.
>
> Yeah, that gives me pause too. I am not really excited about renaming
> every "total group." To quote my comments from a recent off-list
> message (can I quote myself?):
>
> "... Tim Rowe pointed out that [the Pan- convention] means that even a
> non-expert will be able to quickly and concisely associate name with
> definition. Assuming you know the accepted "higher" names for at least one
> taxon containing every extant species (not too bad, since most of it can
> be swept into Archaeobacteria and Eubacteria, you can actually give
> a taxon name for almost any fossil form without knowing ANY
> of the fossil taxonomy.
> I hate to say it, but I find this compelling."
>
> So it may be unpleasant to give up Synapsida,
Rather Theropsida. There will be a talk that will propose giving an
apomorphy-based definition to *Synapsida*; I think this is a good idea.
> but we gain the ability to more effectively communicate with
> people who weren't familiar with the term. Is it worth it?
> I'm not entirely sure. After all, "they" are already getting
> crown clades, maybe paleontology should get to keep something!
B-)
Well. I do think that it's a good idea in general, but not for many details.
It should not become a Rule.
> > SimilarIy, having the name 'Mammalia' anchored to the node of the crown
> > group will not change the imprecise and often subjective usage of the
> > word 'mammal' in the scientific literature. I have a feeling that
> > _Morganucodon_ will continue to be called a mammal, even if it
> > lies well outside the crown group. Ditto for _Eryops_ being an
> > amphibian.
The latter can be stopped; note how people stopped calling dinosaurs
reptiles before (within the last 5 years or so) people started digging up
the definition of Reptilia from Jacques Gauthier's dissertation. The
former... perhaps we should adopt the definition of *Mammalia* by Luo,
Cifelli & Kielan-Jaworowska 2002 -- {*Sinoconodon* + crown-group}. This
would contain *Morganucodon*.
> I partially agree on amphibian as a vernacular term; it has traditionally
> referred to a grade, and, like pelycosaur, it is sometimes useful to
> retain that usage colloquially. However, unlike with pelycosaur, I
> would refrain from using it in scientific literature, because it
corresponds
> to a named taxon with a different content. I am similarly wary of reptile;
> I will use it in the paraphyletic sense when talking to the public, but
> even then I usually qualify it as including- or excluding birds.
This gives yet more support to my IPNM talk! :-)
> Bird is easier, because
> there is no taxon Birdales to confuse the situation.
Try this in Spanish -- ˇLas Aves de Alfred Hitchcock! Or in front of an
audience with some rudimentary knowledge of Latin (over here, this is still
the _norm_).
> I remember Chris Brochu pointing out bemusedly on this list that
> the "supercroc" wasn't really a "croc." Here I draw the line... it is
> not a crocodile, and not a crocodylian, but I have absolutely no problem
> referring to any member of any
> taxon with the croc- stem as a "croc," and it is a croc-form croc-morph.
Sounds artificial.
> "Mammal' is like "amphibian," but you run risk of offending
> paleomamalogists no matter what you do. I wouldn't call
> Morganucodon a "mammal" in front of my advisor. Heck, I got
> lambasted yesterday to talking about "saber-toothed
> tigers," even though I am well aware they are not tigers (the absence of a
> forged steel blade and a basket-hilt on the dentition is apparently not an
> issue...). However, some people would get pretty hot is you said it isn't
> a mammal.
At least this doesn't imply anymore that it were a "reptile"!
> BTW: I DO feel Lissamphibia should be abandoned. For one thing, it was
> originally coined to *exclude* frogs (!).
1. Nobody knows this anymore. All usages I've seen include frogs.
2. In French, lisse means smooth... frogs and urodeles are smooth, while
some caecilians retain fish scales. I don't know if this is the etymology,
though.
> Second, if one follows the
> crown-clade convention, Amphibia is the appropriate name for the extant
> 'phibs, with all the justifications that go along with crown-clades.
The name *Lissamphibia* already exists for the crown-group. So we have to
choose between having 2 names for 2 clades or 1 name for 1 clade. (If, of
course, we don't make up *Panamphibia* -- a name that would cry for
including *Ichthyostega* and *Diadectes*.)
> Third, who the heck knows what a "lissamphibian" is?
> It is not a very widely-used term outside paleontology, AFAIK.
I don't know.
----- Original Message -----
From: "T. Michael Keesey" <mightyodinn@yahoo.com>
Sent: Saturday, June 05, 2004 2:00 AM
Subject: Re: Crown groups
> Why should one form of definition require an affix when others don't? Why
> don't we have affixes for crown clades, too? If there's a _Pancrocodylia_,
> why not a _Coronocrocodylia_, too?
Or a *Neocrocodylia*! (*Neornithes* is a crown-group, *Neosauropoda* was one
throughout the Late Cretaceous...) Or *Neosuchia* (which exists, but is
larger than the crown-group). Or *Eusuchia* (which is a _little_ bit larger
than the crown-group).
> Answer: It would be too disruptive!
I don't know if it would be more disruptive than restricting _all_
well-known names to their crown-groups.
> However, I grant you that it would be nice to tell, at a glance, what type
> of taxon something is. What's the solution? Surprisingly, the best answer
> may be found in the Linnaean system....
>
> How can we tell, at a glance, that Animalia is a kingdom, Saurischia is an
> order, and Glires is a cohort? We can't, if they're written that way. But,
> if they are written as Kingdom Animalia, Order Saurischia, and Cohort
Glires
> (as they frequently have been), it's easy! (In fact, even easier than
telling
> that, say, "Panamniota" is a panstem clade.)
>
> So, why not have the same option in phylogenetic taxonomy? Panstem Clade
> _Synapsida_, Crown Clade _Mammalia_, Stem Clade _Saurischia_, Node Clade
> _Dinosauria_, Apomorphy Clade _Avialae_, etc. Not mandatory, but optional
> for the first mention of a clade, or in the systematics section of a paper
> (much as rank designations are in the Linnaean system). That way we can
keep
> the old names, but mark what the new definitions are.
Sounds like a good idea. But I fear it would stop somewhere. Stem-Modified
Node Clade... Node Clade With Qualifying Clause... :-/
----- Original Message -----
From: "T. Michael Keesey" <mightyodinn@yahoo.com>
Sent: Tuesday, June 08, 2004 3:11 AM
Subject: Re: Crown groups
> --- jonathan.r.wagner@mail.utexas.edu wrote [answering to the above]:
> > Yeah, but that kindof misses the point, which is that you can tell WHICH
> > taxon for which the "pan-" name is the total group: e.g., Panmammalia
> > is the total group of Mammalia. I don't see anything in your proposal
> > that serves this purpose. So then why even bother?
>
> This is true, and perhaps it would be good to have some sort of convention
> for crown and panstem clades, since they are in 1:1 correspondence with
each
> other. It just seems to me that mandating affixes is something we should
we were
> trying to get AWAY from.
I agree.
> I already gave my "Panpan" example of why this would not be a good
> idea in all instances. For some others:
> Is _Panderichthys_ the panstem clade of _Derichthys_?
> Is _Panthera_ the panstem clade of _Thera_?
> Is _Panarthropoda_ the panstem clade of _Arthropoda_? (Well, they might
> try to redefine it that way, but that's not what it means now.)
> Is _Panoplosaurus_ the panstem clade of _Oplosaurus_?
(*Oplosaurus* exists, though only in synonymy lists.)
> Is _Pantotheria_ the panstem clade of _Totheria_?
> etc., etc.
>
> So, perhaps it's a good idea to link corresponding crowns and panstems in
> some way, but I don't see how this could be it. Perhaps we could allow
> hyphens in this one instance (_Pan-mammalia_)? Or perhaps there's
> another solution.
Hyphens... why actually not...
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