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

On 8/23/06, Jura <pristichampsus@yahoo.com> wrote: 

I've read you say this a few times in this thread now.
While I am well aware of the fact that PN can be
removed in favour of a more rank based system in a
cladistic analysis, I know of no case where the roles
were reversed. That is to say, when has PN ever been
used without cladistics (i.e. naming a traditional
Linnean tree using PN)?


_Dinosaurs of the Air_ by Gregory Paul. He gives apomorphy-based clade
definitions to several of his new taxon, but he eschews cladistic
analysis.

That is the only instance I can think of.

I feel that this is more of a cop out than it is an
answer. Both lizards and snakes are members of the
group (order) Squamata, but it's referring to the
names of the subgroup (the suborder) that I'm
questioning. No one says non-ophidian lacertilian
(non-serpentean saurian, or any mix inbetween).


Of course, not, because those are paraphyletic grades already. Those
phrases are redundant.

Yes
one could say non-ophidian squamate, but it's much
easier to just say saurian, or lacertilian.


Those are not well-defined. Are mosasaurs lacertilians? Are worm
lizards lacertilians?

If anything, you and others raise an interesting
point. Why not use/create a higher "level" grouping
that is understood to contain dinosaurs and birds?
Something like "Dinoaves," but preferably more
original (besides I think GSP already used that term).


There's nothing inherently wrong with that idea. But there was already
a preexisintg movement to place birds within _Dinosauria_ (starting
with Bakker), and the idea has become quite popular. It would be hard
to turn the tide against it.

But maybe I'm wrong and it's not too late. Publish something. You
could coin "Avedinosauria" or "Ornithodinosauria", or maybe even give
Huxley's Ornithoscelida a definition! (It was named for Dinosauria
[sensu Huxley, basically non-coelurosaurian _Dinosauria_] +
Compsognathia, and supposed to be a grade between reptiles and birds.)

This would seem to allow for a more accurate
representation of specified groups. Just like how
squamate is still divided into saurian/lacertilians
and serpents/ophidians (and amphisbaenians now and
again) to allow for a greater specification of the
groups within.


But that's not an "accurate" representation of the group, any more
than dividing mammals
into bats and non-bats is an accurate representation of the group.
It's one way of doing it, but there's nothing inherently useful about
recognizing that division *over other similar divisions*.

One could even coopt a term that is already in place
(ornithodira). It would just include pterosaurs as
well (assuming they are still ornithodirans at the
moment).


But we already have that clade.

Well, for one, birds locomote in a manner completely
different from those of dinosaurs (classic dinosaurs).


Bats locomote in a way completely different from other mammals.

I'm not talking about flying either. No dinosaur has
been shown to be a tibia based walker.


I'm not talking about flying either. No mammal has been shown to
gallop in the same way that bats gallop.

I've seen you get pretty heated over this in later
posts. You seem very insistent on stating that words
like "lizard" and "fish" hold no sway in this debate
(and that they basically mean what they were
historically assumed to mean).

Yet, and this part bugs me, everytime a person on this
list says that birds are dinosaurs (or just invokes
the acronym BAD), I see quiet. "Bird" is just as
vernacular as "lizard" and "fish" (though better
defined than the latter). If calling a snake a lizard
is considered bad form (as you and Jaime seem to
suggest), then I'm forced to repost my original
question again.


No matter what usage of "bird" someone has (unless it includes
pterosaurs or bats), Clade _Dinosauria_ includes it. So I have no huge
issue with the phrase. Sure, it would be more precise to say that
avians or avialans or avifiloplumans or neornitheans or whatever are
dinosaurs, but you don't always need that level of precision in
informal communication.

Why is it okay to call "birds" dinosaurs, but it's not
okay to call snakes "lizards?" It just seems like a
double standard to me.


"Dinosaur" is based on a formal taxon; "lizard" is not.

I'd say that dinosaurs, for the most part, were
generaling adapting to various niches as large
terrestrial animals.


The ancestral condition for dinosaurs is as a small terrestrial
animal. (Many extant dinosaurs fit this description, too, to varying
degrees.)

Birds not only became a completely aerial
group (with later moves to the ocean and land again),
but they also show a much smaller size range. Again,
they were also wildly successful at it.


You can make the exact same arguments (minus the marine and
terrestrial forms) for Class Chiroptera.

I admit that cetaceans have done some serious
morphological upheavals to get to where they are. They
are also the only mammal group to be comprised solely
of giants (even dolphins are big). I'd hesitate from
separating them as a class just because they still
retain many of the key features that unite mammals
(the inner ear bones, suckling, etc). They also hold
relatively limited niches, and diversity. Admittedly
though, the latter is probably that limitation of
being big, thing again.


Don't you see an interesting pattern, though? All of your arguments
are subjective. They are based on opinion, not on scientific fact. You
think birds are "really different" from other dinosaurs, but not that
bats or whales are "really different" from other mammals. What's to
prevent someone else to say, hey, I think turtles are are "really
different" from other reptiles, so I'm going to separate them in their
own class? There are no objective criteria. You are arguing for an
opinion; you are not doing science.

The others don't appear to be as derived away from
Mammalia in general, as cetaceans (even bats still
retain fur, the inner ear bones, and still suckle
their young).


Birds retain scales, erect limbs, and still care for their young
(ancestral archosaurian trait). What's your point?

You keep arguing the semantics, but seem to be missing
my point. No one goes around using these "non-"
monikers anywhere but in vertebrate paleontology
(mostly dinosaurs, but I admit that there are cases of
it in mammal paleo as well).


Also angiosperms, if I'm not mistaken.

Phylogenetic taxonomy has not been around long enough for it to spread
to all disciplines.

In the example you gave,
no one goes around saying "non-eukaryotic biote."


Come to think of it, the "biote" part is a bit redundant if it's
already understood you are talking about organisms. You could just say
"non-eukaryote"--but "prokaryote" is already available as an informal
term. It would be like saying "non-vertebrate [metazoan]" instead of
"invertebrate".

You say it's because we have these handy informal
phrases like "bacteria," but we don't have one for
"non-avian dinosaur." I beg to differ. We had dinosaur
before it was hijacked.


If we retain the traditional (pre-1970s, post-1800s) meaning of
"Dinosauria", then we need another name for the (very interesting and
much-studied) clade.

Besides, Prokaryota is an acknowledged group, even if
it was never included as a clade.


So is Invertebrata, and nothing prevents me from using "invertebrate"
as an informal term.

Perhaps if there was a more varied vocabulary in the
terms, this "non-" stuff wouldn't be so bothersome.
Still, after seeing all the examples given, I'd still
think it would be easier to say "dinosaur,"
"theropod," "maniraptor." etc.


But then you have to invent *longer* ways of referring to the clades!
"Avians and dinosaurs", "avians and theropods", "avians and
maniraptors", etc. And these clades are far, far more significant
groups than those paraphyletic groups. Of course, we should be able to
discuss the paraphyetic groups, but why not keep them all on equal
footing instead of arbitrarily picking a few *at the expense of
others*?

_____________________________________________

>> For instance, I do see a
>> problem with the term: "non-mammalian pelycosaur."

> Me too, since "Pelycosauria" is not a clade, and all
> "pelycosaurs" (non-therapsid synapsids) are not
> mammalian, anyway.

+++++++++++++++++++++++++++++++++++++++++++++

I don't see why not having all pelycosaurs being
mammalian has anything to do with the forgoing of the
term.


"Pelycosauria" excludes mammals already. "Non-mammalian pelycosaur" is
therefore redundant.

Not all dinosaurs were avian either, yet "non-avian
dinosaurs" abounds.


Bu *no* pelycosaur is mammalian. Some dinosaurs are avians. Bad analogy.
--
T. Michael Keesey
The Dinosauricon: http://dino.lm.com
Parry & Carney: http://parryandcarney.com