Re: BAD vs. BADD (was: Re: Most popular/common dinosaur misconceptions)

["Jaime A. Headden" <qilongia@yahoo.com>]

Jura (pristichampsus@yahoo.com) wrote:

<There is logic in the old rank system. It provides a nice, relative, guage of
how far apart different animals are.>

  This is not logic, this is aesthetics. There is no "gauge" in ranks to
differentiate how far anything is from anything else, since there is no
explicit means by which differentiation could take place, or how many ranks
relates to how much differentiation. Accomodation in a single paradigm (fish,
mammals and birds divided into orders traditionally) tend to allocate new forms
to Orders before any other rank is placed.

<I do think it could be fixed if there were enough people willing to devote the
time to it.>

  Until then it remains an illogical, unscientific, and almost purely
traditional aesthetic to retain. Use science, and I think one would tend to
abandon rank as superfluous, though that's just me.

<That said, having a relative guage of separation is helpful. For instance if
one told me that _Spinosaurus_ was an offshore of some crocodyliforme lineage,
than I could be able to test that simply by looking at the ranks. _Spinosaurus_
is in the family Spinosauridae, which is in the order Saurischia, which is in
the class (for all intents and purposes) Dinosauria. Crocodyliformes are in the
"class" Crurotarsi (again, for all intents and purposes). So right off the bat,
I know that _Spinosaurus_ is probably not an offshoot of the crocodyliformes
because it differs all the way at the "class level.">

  It seems to me that what you really did was look at a classification and saw
that other people had placed *Spinosaurus* in the Spinosauridae, as a member of
Saurischia, in Dinosauria. Because it is not in Crocodiliformes, it is not a
crocodiliformes. If someone argues that it WAS a crocodiliform, do you think
they would use ranks to do this? I think they'd look at its morphology (as some
have attempted to argue, trying to place spinosaurs as giant bipedal crocs),
and find that spinosaurs are simply theropods. Ranks, in this case, are simply
referrents, and unneccessary to what you were actually doing (looking at a
classification).

<To do the same thing using PN is harder. In order to test the validity of
_Spinosaurus_ is a crocodyliforme offshoot, I have to see where clade
Spinosauridae is, and how many clades away from clade Crurotarsi that is. So
right off the bat I need a cladogram to answer my question (which is done in
cartoonish example so as to get the point across).>

  Here is where thinking of ranks confuses the person when looking at clades.
There are no clades between *Spinosaurus* and Crocodyliformes, simply
definitions, and neither of which say anything about the other. What happens,
what is required, is that the person, as you showed, must use a classification
and apply the definition to the classification. Note that the definition is
independant of the morphology of the animal, as well, but that the morphology
leads to the classification and the definition is based on _a_ classification
(not just one particular one).

<Clade names might remain static, but clade membership, and relationship with
other clades does not. For instance, if some paleontologist somewhere
discovered that _Spinosaurus_ and its kin actually had crurotarsal ankles, and
a few dozen other features that would link it with Crurotarsi (which were
"remodeled" during evolution towards a theropod mimic lifestyle), then
Spinosauridae would still contain all its current members, but the clade would
have hopped all the way into Crurotarsi. So no cladogram, means no way of
answering the question.>

  Which means that what you are really doing is mapping names onto a phylogeny,
rather than shoving a taxon into a position that would not change. For exmaple,
it is the study of morphology, not the rank-based system, and its application
to an organism in a comparative manner that leads to phylogenetic schemes, and
thence to classifications. I see no difficulty in this.

<Long story short, as a disparity guage, the Linnean rank system tends to work
very well.>

  Or, as I have shown, not at all.

<Speaking of, I completely missed another useful example of an arbitrary
system. This one was right under my nose, in the other half of our field. How
about lithostratigraphic classification. The dividing line between one member
and another is not always (not often?) distinct.>

  Yet must be defined explicitly, not based on its content of fossils but by
its lithology. Dividing a shale layer from a sandstone is hardly arbitrary
since shale and sandstone are not the same thing. One can differentiate the two
environmental conditions that would have lead to each, and argue each occured
in a different time. The shale layer gains a monicker, and so does the
sandstone layer.

  What is arbitrary, though perhaps not as much as some systems, is labelling
things members OR formations OR groups OR supergroups. Yet the divisions of
layers are real.

<I have a problem with separating bats partly because bats make up the majority
of mammal species alive today (and probably in the past as well). It would
almost seem easier to call bats mammals, and other mammals something else.>

  This is entirely different from the arguments for cetacean inclusion in
mammals. This is begging that bats are quintessential mammals (they aren't, as
most systematists would argue it is US that are mammals, and we are only ONE
species, such that the attempts to anchor Mammalia to a single set of genera
almost always includes us, otherwise mice or rats [not bats]).

<That aside, the standard definition of a mammal was based on fur, suckling and
the three inner ear bones.>

  A definition, fortunately, not _the_ definition, based on that ol' rank-based
system. And as I noted before (now in the last post), there are mammals that
possess only a few of these, not all, that are mammals by proxy. There should
be a reason (and it's been proposed in print) that monotremes are NOT members
of Mammalia (hence, Theria -- a classic synonym for Mammalia -- for marsupials
+ placentals).

<Bats are different from other mammals, but they still retained all these
features.>

  And as I pointed out, snakes are still lizards, but without the legs. And
birds are still dinosaurs, only with another way to walk and the ability to
power flap (not even all basal birds can power flap). So this seems to be a
matter of personal taste and not any explict means of including versus
excluding members other than that some person put some animals in one rank, and
now it's the "in" thing to do among one's peers.

<Since Darwin, the traditional cutoff has been _Archaeopteryx_.>

  Even the Urvögel had it's detractors since it was discovered (after Darwin's
book, btw). Darwin hardly remarked on it, while Huxley used it quite avidly, as
did Marsh here in the states, in defense of a natural evolution versus its
detractors in people such as Cope and Marsh.

  Yet people disagree, as it is a fossil, and does not embody the (once again)
classic cutoff of birds as those that are alive. This has led to two parallel
definitions (and actually, there are FAR more definitions -- even casual,
non-phylogenetic ones -- of Aves than there are for virtually any other group
of vertebrates) stopping at Archie or at living birds.

  But, as I asked, "WHY stop at Archie?" You say traditionally. If we were to
stop at tradition, NOTHING would change. Science doesn't march on, and we are
stuck in this little dark age. There are reasons why the traditional model
doesn't work, and one of these is science, and another is aesthetics.

<Personally I'd have gone closer to the split between Enantiornithines and
Neornithines (where substantial differences between "classic" dinosaurs
occurs), but it seemed to have been decided long ago that a single character
was more important than a suite.>

  A suite doesn't come into existence de novo, is is gradually built. If we
argue mammals are only mammals if they ancestrally possess each of three
completely internalized otic ossicles, mammary glands, and fur, we MUST exclude
monotremes as non-mammalians, since they lack true mammary glands. We just also
exclude many earlier mammaliamorphs from Mammalia because of the absence of a
fully internalized otic-suite. Yet these are still termed mammals by most
because they _look_ like mammals. This is why the definition has changed over
time. If we exclude mammary glands from the definition to include monotremes,
then the fallacy that is the Linnaean aesthetic is even more transparant.

<So for better or for worse, _Archaeopteryx_ seems to be it.>

  In your opinion, of course. Others (many others) disagree.

<For snakes, the cut lies in the skull and when it reached a specific degree of
kinesis.>

  Much of this kinesis exists in mosasaurs, however. Are they snakes? The
differences snakes enjoy from mosasaurs include the loss of a symphyseal joint
and the reorganization of the skull bones with a loss of mesokinesis (to
strengthen, presumably, the palatal complex when striking prey). Much of that
cranial anatomy is NOT unique to snakes, but includes their own ancestral or
sister stock. Here, again, one is going to have to fall on either one single
morphology, since one would tend to continue including less and less "snaky"
animals before one starts including full on "lizards" in Serpentes; or do as
others do, and simply define the content of a clade to be flexible. Otherwise,
the name would have to be defined with explicit exclusions that would only get
larger as more and more similar "but not quite" animals are found to be
related, and closely.

<I'm running out of time for this post, but for bird I'd say it would be
defined as a bipedal animal with feathers (pennaceous & down), forearm wings,
relatively fixed eyes, and tibia based walking (i.e. they "sit" on their
femora). I'd also add in a lack of teeth and a tail, but like I said. Someone
decided long ago that Aves should start with Archie, so oh well.>

  No one decided long ago anything you have to follow, but it seems you choose
to follow it. If so, take the blame on yourself. So *Ichthyornis* wouldn't be a
bird (it has teeth), despite being a better powered flier than ducks likely
were. *Microraptor*, if using teeth is true, would be a bird, so would
*Caudipteryx* (and by extension, *Oviraptor* -- it even lacks those teeth you
dislike!), *Velociraptor*.... If we go by ancestry, the first appearance of ALL
of these features in a single animal would be *Oviraptor* (if it
crouch-walked), otherwise *Shenzhouornis* (aka, *Jeholornis*) or perhaps
*Jinzhouornis*, which might be the same thing anyway. If you anchor the birds
on toothlessness, *Confuciusornis* would be a bird, and it even has a
pygostyle, while toothed enants, which you earlier argued WERE birds, would not
be, and they are even closer to living birds than *Confuciusornis* is.

  The problem with the paradigms, is that they are both convergent, and
ancestral. Suites are assmebled in time, rather than appearing de novo, and
there will be species who will NOT have all but just some, and more who will
have most, but not all, and finally all but one, and yet not be a bird. Why?
Who knows.

  By the way, the tradition icon for marking a bird is nothing short of only
ONE character: Feathers. Your suite up there flies in the face of popular and
traditional definition based on morphology.

<I'd take an all, or nothing approach to the hypothetical cutoff too.>

  Then you would certainly start paraphyletically excluding a host of true
birds. Kiwis, while ancestrally avian, lack plumullaceous feathers AND
forewings. And the animals I noted above that have all these features, but are
typically non-avian dinosaurs. Yep, I used the term, simply because it's
useful. 

<That is, a dinosaur would have to have all the above to be called avian.>

  Like *Oviraptor*? And all animals descended from it, even if they reversed
the condition?

<An avian would probably have to lose all of the above to be called something
else, but that gets a little too forward thinking and dangerous.>

  Actually, that sounds like more of the same thinking, not forward, but
certainly almost backward. It has to have ALL to be a bird, but it has to LOSE
ALL to be a nonbird? This is simply not even logical.

<My argument was that "croc" would be a term best served if limited to eusuchia
(where it has traditional stayed until relatively recently).>

  And I argued in that discussion that there is no reason why "croc" could only
apply to Eusuchia, as this would exclude a number of diverse and croc-shaped
noncrocs within Crurotarsi. Most of them semi-aquativc, sprawling,
croc-snouted, like the pholidosaurs, *Goniopholis* and even dyrosaurs. Indeed,
the only difference between Eusuchia and crown crocs is *Hylaeochampsa*, and
there is nothing that different between *Hylaeochampsa* and slightly more basal
crocs such as *Sarcosuchus* or *Bernissartia*, that we should exclude them from
the concept by fiat! Eusuchia doesn't even vernacularly refer to "croc", so the
intuitive link is lost, instead we must use eusuchian (as many do), while
"croc" is usually applied to names with the letters "c-r-o-c" in that order in
the name itself, and its applied to things like sphenosuchians, phytosaurs,
poposaurs, aetosaurs, etc, some of which aren't even crocodylomorphans
(traditionally, even!). This is an example of more nothing but taste.

<If you don't think calling other crurotarsans "crocs" is a problem, then I'd
direct you to review the old e-mails related to the discovery of _Effigia
okeeffeae_  and see the complaints about the fact that: "it wasn't a croc. It
was a poposaur.">

  Really. I was arguing it _was_ a croc (as in, Crurotarsi). But that simply
goes by the same people who look at graphic image and thus apply the lay term
(which was introduced to the public, as dinosaur was, by way of the formal
name). But anyways, the point is that there ARE people who misuse terms in both
a vernacular form and a paraphyletic one. The solution is not to bow down, but
to educate.

<Er, no. I've already given you plenty of examples where arbitrary definitions
are in effect today, and are still useful. Obviously I don't mean subjectively
arbitrary things. I'm referring to things that are generally agreed upon in the
field (e.g. group, formation, member, etc).>

  And I have given some examples here and in the previous post why some of your
examples are confused, in that nomenclature is always subjective, but at least
in geology, the divisions noted are NOT arbitrary but recognized. That they are
labeled "formation" and given a name "Hell Creek" does not equate to them being
stratigraphically differentiable. The same is true for a bird and croc; while
anyone can tell the difference between a bird and a croc, one is hardpressed to
determine why this is so, without defining bird and croc, and when one begins
to put animals into one category or another, they must check it against their
argument; If it checks, then so. Phylogenetic definitions are a check, and so
are morphological suites. However, above I asked how one defines a bird, and I
was given not just a list, but the reasons I asked for on how to assign a bird,
and there the usefulness of that definition ended in a heap. It's suddenly
about using "bird" as a phylogenetic qualifier, rather than a vernacular form.
What I had asked what the definition of a bird, not the definition of a taxon
Aves, and I had thought to make this clear by the use of "Bird" (in quotes).
Since the two were comingled in the response, I am at least grateful that the
term in the vernacular is applied at least to some level to the scientific.

  Now consider how you would define and distinguish a "bird" if I were to ask
you to use the available nomenclature:

  Paraves, Avialae, Pygostylia, Ornithuromorpha, Ornithurae, Carinatae,
Neornithes.

  Why are these used, but not others? Paraves, the "around the birds" is
defined as {the most recent (or last) common ancestor of *Deinonychus* + [some
bird, I prefer *Passer*] and all of their descendants}, and Avialae as the
first animal with fully developed flapping arms [read: wings] consistent with
*Vultur* and all of its descendants}, while Pygostylia seems to have two (a
pygostyle as in *Vulure* and *Confuciusornis* + [some bird]). And so on, and so
forth.

  Aves fits in their somewhere, depending on what people would agree on to be
Aves, such that it could include all of them, some of them, or be synonymous
with the last.

<Another prime example is that of the IAU and how that group has gotten
together to agree on the arbitrary criteria that make up a planet. I don't
remember seeing you complain too much about that (deciding that Pluto should be
the cutoff point, yes, but not the actual criteria itself).>

  The actual criteria really don't interest me, as long as the definition is
scientific. I would follow this if I could not think of a more compelling
scientific definition that suited me better (and by "suited" I am tying this
into "more compelling scientific"). However, the definition as I understand my
astronomical geology well enough seems to be very satisfying, especially given
the origins of the inner planets, the formation of the asteroid belt, and the
various events that seem to indicate the gaseous giants used to have a few
interspered members of some size or other and that some bodies crossed orbits,
collided, or were captured (as in Titan). That no moon is being considered a
planet I do fret about, but it's something I raised in another forum, since
this is not an astrogeology forum. But why would that be important, anyway? I
did raise concern that the definition hinged on including Pluto as a matter of
taste, but I am happy there was a definition, since now there is one, it can be
hammered out and argued over more explicitly -- and, I might add, at least
SCIENTISTS defined the term, and not laypeople who must then expect the
nomenclature and use in science to follow suit.

<Youc can change the boundary, but you'd have to publish your findings and see
if they are agreed upon.>

  I would not change the boundary without a scientific reason. And I certainly
can't think of a scientific reason to change a clade's definition (as the
descision to frame a definition is one of arbitrariness and taste, even if the
nature of the definition itself is scientific and objective), though I can
think of one [several!] to abolish ranks.

<This does occur with actual phylogenetic relationships too, as is amply shown
by the dearth of people who accept Feduccia's phylogeny of dinosaurs.>

  Ah, Alan Feduccia doesn't have a phylogeny of dinosaurs, he has a bit of bad
taste heebee-jeebees in so far as that he tried to frame an alternative based
on taste (that _B_irds _A_re _N_ot _D_inosaurs, for the same reasons it might
seem you would argue against it). Feduccia simply tries to frame his model (or
rather, Martin does) by trying to point to another ancestor, without tying them
in any reproducible way. This is why it fails. There was no taste-based
ignorance or rejection, since the models were debated and argued over for
weeks, and continue to be done so every 3-4 months on this list.

  Now I am one to ask WHY names are ignored, if either useful or applicable,
and have gone so far as to defend (once) Stephan Pickering's "publications" as
they accrded by the ICZN, yet failed that argument because of the criteron of
availability. If the reason is scientific (general ignorance leads to a
rejection of use in favor of another, entrenchment of a name, more chaos to
dredge a name than otherwise) I will follow because I cannot think of a reason
why not to. But I do try to be consistent.

<I'm not sure what those two taxa were doing exactly. I haven't heard any real
talks about _Microraptor_ being an active flapper (vs. gliding), and
_Caudipteryx_ was showy, but earthbound.>

  Yet "flying" or "flapping" aren't in your "bird" criteria; only feathered
arms, which both of these taxa possessed.

  Cheers,

Jaime A. Headden
http://bitestuff.blogspot.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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