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*Archaeopteryx* Is Not A Penguin ... But What About A Dipper?



HP Jaime A. Headden wrote:

>   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)

, in which even Ostrom himself doesn't believe any longer,

> 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!

Exactly. Unlike Ebel, I don't think wing feathers are an adaptation to
underwater flight, instead I use Hopp and Orsen's hypothesis, which
perfectly well explains the evolution of *wings* (and maybe even that of the
semilunate carpal -- "brush-odynamic"), but *not* that of *flight*.

>   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.

If theropods had begun to swim without already having wings, they would
(contra Ebel) never have evolved wing feathers, instead the outcome may have
been something like a penguin. So I can assume that there was a selective
pressure that kept the wing feathers on theropods. Brooding is the activity
that comes to mind. Penguins don't use their wings in brooding...

I have thought about this rather late, but before publication, and that's
why I have introduced the dipper analogy. I'm not going to tell anyone
*Archaeopteryx* was truly aquatic. This is obviously nonsense. Semiaquatic
is a much better term for what I (respectively Ebel) mean.

> 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.

Well, either the feathers were covered with that fatty secret -- isn't that
a plesiomorphy for Neornithes? -- like in most birds today, so they would
not trap any water, not even get wet, or they were not, like in cormorants
(don't know for pelicans and anhingas) -- cormorants actually enjoy this,
because feathers that can get wet don't trap *air* and thus make diving
easier.

> 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.

Erm... Penguins have wing feathers? Real remiges, I mean?

>   Close examination by Hecht, Viohl, Wellnhofer, Ostrom, et al.,
[for politeness not mentioning Feduccia B-) ]
> 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.

The dippers are passerines!!! Just as I quoted, dippers have one adaptation
to their particular lifestyle, the skin flaps over their nostrils which
won't fossilize.