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*Archaeopteryx* Is Not A Penguin
David Marjanovic wrote:
Heh, heh, title says it all.
As Tom Holtz has stated, and you can use the calcs Jim
Cunningham has supplied, plus about 5 other reputable papers on
flight performance in *Archaeopteryx*, all the wing mechanics
and body shape suggest that the animal was airborne, not
[Sheesh, doesn't Feduccia realize that the "solid" feather is
arrived at secondarily to the pennate morphology, if more
primitive forms can possess a fully enpennated feather? Further
comments on the list when *Protopteryx* was described.]
Okay, back to premise, which is this:
To describe the hypothesis that *Archaeopteryx* developed its
flight structure as an aquatic form, one must denounce previous
hypotheses for the origin of flight. Not to say that this is an
absolute statement, but it _is_ good science. Aside from the
trees-up, and ground-up theories, there was Ostrom's original
mutation (the "flyswatter" hypothesis) and Hopp and Orsen's
brooding-made-wings theory, which really is a nice and
well-reasoned concept and I am grateful to Tom for allowing me
to examine it, as much as I am interested in brooding in birds
-- oviraptors, you know!
However, there is one major flaw in David's hypothesis, and
that's the form of the feathers: penguins have reduced the
retrices and remiges. Water is a lot denser and therefore
provides much more drag as molecules moving over a structure
have increased 8000-odd%. Having a longer feather or
flight-surface will increase drag by increasing the aspect ratio
of the structure. Penguins cope with reduced feathers by
increasing the power in the arm and the surface of the arm to
provide thrust, but extraneous feathers are now surface
streamliners. The feather itself acts to increase drag in the
water, and will trap water between the barbs and barbules,
making it more difficult to move the arm or tail, so if you see
a diving pelican, or anhinga, or osprey (birds that dive deep to
get prey up to a meter below the surface) struggling to get back
out (they don't launch like ballistics, you know) this is why:
trapped water. In better context, a feather suited to water
would be one that provides a near solid surface over which water
can flow, and drag is reduced. This occurs in penguins, though
not because the feathers are "solid" or sheet-like in anyway.
The barbs overlap, providing this.
Close examination by Hecht, Viohl, Wellnhofer, Ostrom, et al.,
has shown that the feathers of *Archaeopteryx* are just like
those of normal birds, only apparently lacking an aftershaft,
which is no biggie (I may be wrong on this), and the wing (as
Heilmann has shown) is structurally and in aspect resembles many passerines.
Jaime A. Headden
Where the Wind Comes Sweeping Down the Pampas!!!!
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