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RE: Archaeopteryx with bird book, was Re: Archaeopteryx flight



John Hunt (john.bass@ntlworld.com) wrote:

<This is all really cool stuff about _Archaeopteryx.  The fundamental questions
asked following its discovery still lack a definitive answer.  Is it an avian
dinosaur or a non-avian dinosaur with wings?>

  Well, actually, the question asked was whether it was a bird or not (Andreas
Wagner said "No!" or something to that effect). Back then, there were two types
of animal, reptiles, and birds, and mammals were only there to classify them.
Fish were inconsequential, and obviously cephalopods felt no pain so were lower
than dirt on the Golden Ladder. In the end, the distinction between what is a
reptile and what is a bird has become so thin as to spill into one another, so
people trying to maintain the distinction are rescuing old use as the savior of
Reptilia to exclude birds. Phylogenetically, however, as well as following
basic anatomy, they are in fact reptiles, so the issue of the question has
largely been answered. Critics of today still use the old
'hot-blood/cold-blood' distinction to revive the antagonism of 150 years ago
between Huxley, von Meyer, and Wagner on the nature of the "avian" beastie in
Berlin (helped, of course, when London got their hands on their own, which
reportedly Marsh passed over thinking it was too inconsequential to him, as he
was looking a HUGE animals from the Bridger out west, not tiny this odd things
from Germany. Certainly, had Cope gotten hold of it and studied it, we may have
had an entirely different story to tell).

  Thus the question is really about semantics and what you want to call a bird,
or "avian". And that's a whole 'nother kettle of *Knightia*, I might add. since
the application of a name to various positions in a family tree, like Aves,
which has variously been the now Avialae, the Archie + other birds group, the
birds but not Archie group, the clade now commonly called Neornithes (and
sometimes their close relatives as fossils like lithornithids when they were
more basal than palaeognaths), and various positions in between now featuring
names like Carinatae, Ornithothoraces, Pygostylia, etc. "Birds" have been used
variously along these, often evoking either a historical usage, a particula
morphology, a condition of powered flight, or to have to include
*Archaeopteryx* due to use as "the first bird." In my opinion, this is a true
"missing" link, as I quoted before it seemed to be an animal caught in the act
of becoming a bird, and in this case I used the "bird" sense of living flying
animals, so _obviously_ I am not treating ostriches as "birds". See what I mean
about semantics?

  And apparently Archie also had wings, a concept hard to pass by. But defining
the word wing and applying it are two different issues, and will require what
to do with flying fish "wings", modified gills in insects made of chitin,
bony-sparred skin-spanned structures in bats, and the slatted, keratinous
structures radiating from along the arm of a certain subgroup of dinosaurs.

  In the end, it will require concensus and standing useage in one way or
another to "define" the words for the future. There are always dissenters, some
main stream and some outre, off-the-map objectors (conscientious or not).

  But being able to determine the osteological features of a birds' wing in a
fossil is, while easy for a fossil partridge, might as well be impossible for a
far more basal form such as *Microraptor*, once again needing concensus, or a
more implicit understanding of the evolution of the animals, regardless of limb
design, in order to put the limb structures into context. Biomechanics helps a
lot ;).

  As for feathers ... what are they, anyway? And what would you call a feather
in the evolutionary scene? Does it have to be the pennaceous, barbed vanes in
flight-feathers? can they include down, chick down, tufted-rachis, "whiskers"
in turkeys, all which have the same origin? These features are found in various
dinosaurs, such as NGMC 91 (aka, "Sinornithosaurus") and *Dilong paradoxus*.
But are they feathers? Some would say birds are those with feathers, so many
would object to *Sinosauropteryx* or *Dilong* being classified as birds, and
now must disprove this case ... which is why semantics are important to work
out before proceeding.

  Cheers,

Jaime A. Headden

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


                
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