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Do 3 middle-ear bones really = 1 mammal? (was RE: SCIENCE AND CLA SSIFICATION)
Ken Kinman wrote:
>But we now have sufficient data to define Aves in a more scientifically
>rigorous fashion (osteologically), just as was done with Mammalia >decades
and this howler...
>The new definition of Aves, if done correctly, will do for birds
>what has so long been successfully done with mammals.
"Decades ago" the Mammalia was thought to be polyphyletic; Simpson himself
carried the banner for this cause.
>presence of hair and lactation roughly corresponds to the scientific
>definition, so there have been no big problems reconciling the two
Ah yes, the "three-ossicles" thing. Check out Cifelli's paper in JPal - it
might set you straight on how "easy" you believe it is to define a "mammal"
anatomically. Short version: It ain't easy, and mammal paleontologists
don't pretend that it is.
David Marjanovic wrote:
>Nope. Nopcsa explicitely starts with a bipedal Proavis, and AFAIK with
I thought so.
> BTW, going to any of Vienna's university libraries -- for example --
> does hardly give one the exercise of walking, unless you are content
> with 5 minutes,
You live in Vienna? Cry me a river, David. You live in one of the most
beautiful cities in the world - take a scenic route to the library. ;-)
>and I wouldn't call the usual street air outside of the
> subway and bus/tramway "fresh air", neither the one in the libraries
Ah, life in the urban jungle...
Timothy J. Williams
Iowa State University
Ames IA 50014
Phone: 515 294 9233
Fax: 515 294 3163
The new definition of Aves, if done correctly, will do for birds
has so long been successfully done with mammals. The scientific
will be precise (osteological), but it will roughly coincide with the
presence of "vaned" feathers. All those more primitive "protofeathers"
Sinosauropteryx, the newly-discovered pterosaur, and even that
bristly-tailed psittacosaur, are apparently just that (PROTOfeather
homologs). Whether the structures of Beipiaosaurus are best regarded as
advanced protofeathers or primitive vaned feathers remains to be seen.
any case, a precise osteological definition should take precedence over
feathers, eggshells, origins of flight, and other characters that
poorly (and that obviously includes bird excrement as well). :-)
Within this new context, the evolution of brooding and powered
the ornithoid eggshell evidence, and so on, will begin to make more
and it will also clarify many of the debates that have paleontologists
ornithologists insulting each other in the press and in other public
(fora?). The whole Longisquama debate is one of the more embarrassing
I am proposing a long-thought-out, moderate paradigm shift that I
believe will enhance stability. Both scientists and the public alike
have to learn that the old "bird = feather possession" idea is
and out-of-date. But shifting to the possession of "vaned" feathers
the best way to accomplish a smooth transition (especially with the
What we now have is confusion and taxonomic instability. The question
my mind is not *whether* we should draw a new line, but *where* it
drawn. To continue drawing the line at Archaeopteryx (eclectically or
cladistically) is a tradition that I think we must abandon for
More generally, we are faced with a decision between: (1) an
emphasis on apomorphy (character)-based taxa or (2) a purely cladistic
emphasis on node- and stem-based taxa. The latter seems to sacrifice
stability of content in favor of stability of definition (definitions
cladists are already fighting over, requiring a new bureaucratic code to
settle them, and no sign that its decisions will be widely followed
If you look at it from a broad perspective, all classifications
arbitrary and "typological" to some degree, and pure cladism is just
promoting a new form of arbitrary "typology". Benton (2000) has already
pointed out that in the end, we will be no better off, and thatin many
we will be much worse off if we follow this path. The pendulum has
too far already (swinging so far, that even I have been ousted from the
"Cladists Club", which is very odd because some eclecticists think I'm
much of a "cladist").
Anyway, I certainly look forward to Mickey Mortimer's upcoming
analysis. And I will seriously consider it's outcome as I continue
searching for a precise osteological definition of Aves that can be made
more precise in the future (as has been done with the Mammalia
------ Cheers, Ken Kinman
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