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

[Jura <pristichampsus@yahoo.com>]

For sake of efficiency, and to avoid steering the
initial point of the dinosaur misconception thread
away, I?ve combined my response to HPs Tim Williams
and Jaime Headden, into one post, and retitled it.


Tim Williams twilliams_alpha@hotmail.com wrote:

> I would opine that if it is "confusing and          
  > disconcerting" than the onus is one you to get    
  > acquainted with the science behind phylogenetic 
> taxonomy. On the whole, I think biologists and      
> paleontologists have done a pretty decent job       
> explaining the rationale behind this system of      
> taxonomy - whereby organisms are united by common   
> descent, not by >some perceived (and highly         
> subjective) quantum of 'difference'.

This quantum of difference is no less subjective than
the choice of characters input into a cladistic
analysis. In fact, prior to cladistics, those
characters would have probably provided the diagnostic
base for naming that particular group of critters.

>> might also crop up now and again, but I've yet to  
>> see it (admittedly the lacertillian one doesn't
show >> up mostly due to the weirdness of lacertillian
    >> phylogeny).

> Again, what's with all the judgements?  Why is      
> squamate phylogeny so 'weird'?


I was commenting on the rather slip-shod way that
lacertilians were originally placed taxonomically, vs.
what we now know about their radiation. If you don?t
think squamate phylogeny isn?t a little weird, then
see Fry et al?s (2005) work on venom glands being
widespread among squamates. They nest iguanians well
within scleroglossa. That?s weird. Of course, that?s
also molecular based.

>> This particular thorny part of taxonomy seems to be
>> limited to dinosaur paleontology

> You can't possibly be serious.  Have you seen       
> invertebrate taxonomy lately? There are similar     
> examples to the birds-are-dinosaurs issue there, as 
> exemplified by the 'phyla' Pogonophora and          
> Vestimentifera now being regarded as specialized    
> annelids; body lice (Phthiraptera) evolved from     
 > within the Psocoptera; and so on.  Closer to home, 
    > whales are now regarded as derived artiodactyls.
    > Cladistic classification is now standard, not
some   > aberration limited to dinosaurs.

So these papers you mention, do they refer to annelids
now as ?non-pogonophoran annelids?? How about
?non-cetacean artiodactyls?? My argument has never
been that cladistics is a bad tool. On the contrary, I
have argued for it numerous times when it comes to
properly figuring out who?s related to who. My
complaint is with the use of cladistics in
classification (i.e. phylogenetic nomenclature, as HP
Marjanovic pointed out in a prior post).

> If it all started in entomology, why do you claim   
> that cladistic classification is "limited to
dinosaur > paleontology"?  You seem to be arguing
against       > yourself here.
 
Because it is. Cladistics started in entomology.
Phylogenetic nomenclature seems to have started in
vertebrate (dinosaur) paleontology. Class, order,
family and all the other ranks still abound in
entomology. So too in herpetology, and other realms of
paleontology that aren?t focused on dinosaurs (I
suppose the correct ?phylogenetic? term for that would
be: ?non-dinosaurian paleontology?). Only among
dinosaurs do I see the ?non-? phraseology pop up
(notable exception goes to HP Chris Brochu?s work on
crocodyliformes).

Jaime Headden <qilongia@yahoo.com> wrote:

>> Calling a bird a dinosaur is a completely different
>> thing from calling a bat a mammal. It is more akin
>> to calling a mammal a therapsid, or a snake a     
>> lizard.

> In this, the contra-comparisons are false. A lizard 
> represents an Entirely different entity than a
snake, > often entailing only the sister-group of all
snakes  > including all other living lacertilians.
That snakes > are members of Lacertilia, yes, as
mammals are       > members of Therapsida, and birds
are members of      > Dinosauria. It used to be that
bats were NOT         > considered members of
Mammalia, but were included    > with birds by
Linnaeus. 

I?m afraid I don?t quite get what you are saying here.
Why is it okay to call a bird a dinosaur, but it?s not
okay to call a snake a lizard? Especially when you
seem to be in agreement with Pianka & Vitt on just
that, further down in the post.

As for Linnaeus, I don?t see the point of using him as
a counter example. He did a lot of good things for
taxonomy by giving us a classification system that
works (and IMHO still works far better than
phylogenetic nomenclature). Other than that, though,
he got everything else wrong. He included sharks as
reptiles for crying out loud (all under one of the
first wastebin taxons: Vermes). That his understanding
of the relationships among creatures was?lacking,
should not come off as a surprise. Back then, all of
this was new.

> The only change that occured "between" the two
groups > is equivalent to the change that occurs
within them  > at any particular given split. Say,
Galliformes from > Galloanseres. 

Just because the initial change from theropod to
_Archaeopteryx_ was small, doesn?t mean that labeling
that spot as a nomenclatural splitting point, isn?t
useful. From Archie (presumably), birds went off in a
completely different direction from dinosaurs, and
became wildly successful at it. This is like how
snakes went in a separate direction from lizards, and
became highly successful at it. Separating serpents
from saurians has proven to be very helpful, and still
no one denies that snakes evolved from lizards. 

> Cetacea from Mammalia involves some massive changes,
> but it is actually rather ridiculous that we not
call > whales mammals because they don't look like
other    > mammals.  

Cetacea never evolved from Mammalia. It evolved within
Mammalia. I don?t think there was ever any real doubt
that whales were mammals. Well, at least after it was
found that they really weren?t fish. They still fall
in as mammals on morphological grounds, even if they
have evolved back to a water bound life. The same goes
for bats (the morphological thing, not the water bound
thing). 

>> Of course I'm referring to the term: "non-avian   
>> dinosaur" to indicate what was originally just    
>> called a dinosaur.

> And so phraseology can change as we start to        
 > incorporate descendants into wholes?

Did you mean ?can?t change?? Then I?d say yes, if the
incorporation only leads to confusion and the erection
of new terms to denote what the old ones mean. So I?d
say no to ?non-avian dinosaur? just like I?d say no to
?non-eukaryotic prokaryote.?

>> I can think of dozens of papers that have come out
>> over the past decade where the term "non-avian    
>> dinosaur" could be replaced simply with the term  
>> "dinosaur" without changing the paper's meaning one
   >> bit.


> Escept that they are usually attempting to exclude  
> the modern avians who have acheived a variety of    
> niches, ecomorphologies, metabolic changes, and     
> morphologic variations not otherwise available,     
   > especially since the average avian is about 1%
the   > size of the average non-avian among most of   
      > Archosauria. They can as easily use non-avian 
      > archosaur and acheive similar results, but
non-avian       > dinosaur restricts the field,
non-avian theropod and > non-avian coelurosaur
further.

How is using a separate set of nomenclature for birds
and dinosaurs (as was traditionally done prior to the
1990s) worse? Why is a hypothetical cut-off point so
hard to accept? Especially, when accepted hypothetical
boundaries abound in other fields of science (more
below).


> Take us to your non-gavialid crocodylians, your     
> non-testudinid chelonians, your non-equid           
> perissodactyls....

None of those are comparable examples. All are
sub-members of the groups you mentioned. If gavials
were found to have evolved from alligatorids (one
family evolving from another family), then something
like non-gavialid alligatorid would be a better
example (and would receive just as much criticism from
me as non-avian dinosaur). For instance, I do see a
problem with the term: ?non-mammalian pelycosaur.?

Fundamentally this is an issue about ranks. There is a
general disdain for ranks from cladists (and most
active members of this list), simply because the
determination of the rank is an arbitrary one. For
whatever reason there seems to be this view that if
it?s arbitrary then it?s useless scientifically. 

This makes no sense. The basics of so many aspects of
science are arbitrary in nature. Look at SI units such
as the meter. Prior to its ties to light, it was once
measured as the distance between two engraved lines on
a platinum-iridium bar. Before that, it was measured
as 1/10,000,000th the distance from the equator to the
North Pole. Talk about arbitrary. The second was no
better. Its current definition is defined as the time
it takes a Cesium atom to vibrate 9,192,631,770 times.
Both are completely arbitrary in nature, yet look at
all that man has accomplished thanks to these units.
The same can be said for the arbitrary way in which
atoms are represented on a piece of paper, or in
models. Their fundamental properties may be arbitrary,
but the proportional relationships garnered from them,
are not. 

Same goes for the old Linnaean rank system. It does
nothing to remove the validity of one group evolving
from another. It just places invisible boundary points
to allow for our brains (which seem to need to
categorize things) to better grasp the material. The
biggest thing the Linnaean system had going against it
(besides being founded during a time before the
acceptance of evolution) was that it didn?t have
enough sub-divisions. The results of which have led to
messy things like infra-orders and the lot.

One might argue (as HP Williams pointed out for
planets) that life is a continuum with all points of
separation being arbitrary in nature. As such, these
arbitrary separations should be dispensed with
(whoopty doo, we?re all bacteria). Again, just because
the separation points are arbitrary, doesn?t mean they
are useless. Look at the electromagnetic spectrum. Red
might start at 630 nm and Violet might end at 380 nm,
but the interim between (and beyond) is full of one
colour bleeding into another. There is no real cutoff
point, just an arbitrary division. Nonetheless, these
divisions have been immensely useful to human society.
Admittedly Crayola has probably gone too far in its
divisions, but that?s more of an economic problem than
a physical one. My point is that we don?t go around
calling colours things like non-green red, or
non-violet infrared. All it would do is make things
confusing. 

Finally in regards to some of the jabs at one?s
scientific education that I noticed regarding the
rejection of the ?non-? monikers. I would like to
point out that the knowledge that mammals evolved from
therapsids, had been established long before
phylogenetic nomenclature came to be, yet still the
two remained separate groups (as well as pelycosaurs).
Further, there are many non-cladist scientists (who
still use cladistics) out there. Most notably on this
list (and I?m going to sound eerily like Ken Kinman
here) would probably be Michael Benton. Even
cladistically minded herpetologists like Eric Pianka
and Laurie Vitt, still use classic ranks for
classification (families, subfamilies and the like).
Rejecting the use of ?non-? monikers isn?t done
because of a lack of understanding of evolutionary
relationships. It has more to do with avoiding
confusion, as well as excessive lumping.

Jason ? who thinks we should dump Pluto and be done
with it. All it was ever good for was being the
exception to the rule for all the other planets.


"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." - Alfred S. Romer

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