Re: Cost in Aquatic Birds (long)

["Jaime A. Headden" <qilongia@yahoo.com>]

David Marjanovic (david.marjanovic@gmx.at) wrote:

[on dippers being conditional to many of the previous points I made about
the nature of the mechanics and anatomy that I use to preclude
*Archaeopteryx* as being aquatic]

  The use of dippers (*Cinclus cinclus*, Cinclidae, an ally of the wren
and closely allied to the Troglodytidae [of which wrens proper are a
member]) is flawed [again] by the very nature of it's lack of aquatic
features. Applying the lack fo these features then to a fossil makes this
even so more problematic to derived any positive evidence to support the
theory. There is no other means by which we can know *Archaeopteryx* may
have had any aquatic behavior, as all this data on dippers is just that,
behavioral. It does not fossilize. To apply behavior to a fossil is a
long-frowed upon practice as it in no way imparts positive, testable data
and thus is no evidence of anything.

<For a bird Archie's wings are pretty short.>

  granted. This imparts no disadvantage to flight, however, except to
moderate ability.

<This is the _strength_ of the hypothesis. I can _decouple_ the evolution
of _wings_ and the evolution of _the wing stroke_. Why have wings? For
brooding sensu lato. And whatever sorts of display.>

  There are easily hypotheses that more easily explain the wing stroke of
archie without having to plop it in the water. In fact, the form of the
scapulocoracoid, humerus, and forearm all suggest that modified arm
anatomy has occured. It's up to the nature of the muscles on these bones
that can assist in knowing wether the animal could use a flight stroke, as
well as the shape of the humeral glenoid. Archie has these features, for
the most part, though relatively reduced compared to later birds.
Therefore it seems that there is no logical reason why this animal would
need to persist in a maladaptive environment to explain the flight stroke.

  There are countless reasosn why Archie is best conceived as terrestrial
or semi-arboreal in nature, and it is up to Ebel or Marjanovic to explain
how the aquaeous environment may have been better suited to explain the
anatomy of Archie (not just the wingstroke) when physics appear to tend to
make water a bad place to be for this animal.

<I don't think so.>

  To jump from island to island would suggest that the animal would need
to be terrestrial in nature. Otherwise, why not stay in the sea?

<Just as dippers ignore it? :^)>

  Dippers are in, then out. They thrust strongly, and get out in a hurry.
Not as bad as osprey diving....

<Unlike Ebel, I don't think the arms elongated _after_ diving behavior
evolved, but before... for... brooding. :-)>

  A condition that would have provided the flight-stroke as a side-effect
to the folding mechanism, rendering the water unneccesary.

<I know they are the exception. That's what makes them fascinating. :-)>

  Because the only thing that puts them in the water is their behavior,
not anatomy.

<No shorter than Archie's AFAIK.>

  Dipper wings are longer and tapered.

[on thunniform bodyshape:]

<Do dippers?>

  Looking at pictures and footage of dippers diving and not, no. And
certainly not *Archaeopteryx*.

<Looks like insects have done it: evolved tracheal gills, later flapped
them for swimming, later flapped them for skimming around while standing
on the water, as stoneflies still do, then flapped them for flying.>

  Insects *started* in the water, and stonefly _larvae_ stay in the water,
but so do "hookworms" (dragonfly larvae). These are amphibious qualities.
Besides, the sequence above is conjectural, and fossil data is so far
lacking on this conclusion.

<"Became so highly derived" is not what I think happened to the
[hypothetical] diving ancestors of birds; when you already have wings and
laterally-facing glenoids, it may largely be behavior, just as you wrote
diving in dippers is just behavior.]>

  The data suggest that many of the features found in Archie are
scansorial or arborial (or cliff-clinging) in nature, including claw
geometry (Yalden, 1985, 1997), and the fossil data from animals from
northeast China suggest that the arboreal features of near-shore paravians
were predicatory to the flight-stroke. The grounds-up and trees-down and
even George's BCF all indicate this, and instead of going with the flow,
this is apparently the most logical argument. You take behavior as a
quality that cannot be substantiated, and thus should render the point
moot.

<Then dippers are not adapted to swimming. Then maybe Archie was just as
> little adapted to swimming. :-)>

  Take that a little further, and instead of trying to put Archie in the
water, you think "Archaeopteryx doesn't have any features that could
actually indicate to me that it was able to swim or would have provided
the later birds (Pygostylia) with the flight stroke -- in fact, evidence
suggests that Archaeopteryx may have already have had something similar to
the flight stroke ..."

  The note that even Confuciusornithidae lack the Ornithurinae triosseal
canal and any form of humeral rotation at the glenoid, thus even a more
advanced bird _still_ doesn't have this quality. Archaeopteryx was
apparently unsuccessful if it _did_ do this.

<Why maneuvering?>

  Advanced wrist, elbow and shoulder joints as found in modern birds
indicate a lessened ability to control the wings in a stroke, muscle
attachment do not look impressive enough to compensate, indicating a
generalized up--down or forward--back ability, but not both in a scenario.
This would require adequate, missing musculature in the humeral elevators
and posterior flexors (deltoideus and scapulohumeralis), indicated in the
proximal and distal scapular morphology, and the horizontal, parasagittal
position of the scapula.

<*Pelecanimimus*? Really? -- Forgot the serrations on the posterior teeth
of *Sinovenator*. Anyway, only a well-resolved phylogeny will be able to
tell whether they (and those of *Protarchaeopteryx* and dromaeosaurs) are
a reversal.>

  So I guess the well-resolved enough? 6 max trees produced by the
Sinovenator analysis is not pleasing. Very good stats regarding homoplasy
and consistency, and it is becoming evident that this relationship is
closest to the "true" tree than any other published analysis. The absence
of serrations, as I hope to show soon, is a mechanical behavior related to
tearing tissue. Animals that lack it are adapted to not tearing with the
teeth, and dietary features of the teeth cannot be relied upon for
phylogenetic information. Many dental characteristics are adaptational and
this is why you see so many unrelated mammals with similar dentition
without exceptional features. Until recently, the crush-and-tear
morphology of the trigonid--talonid structure was considered informative
of a monophyletic group, and this is no longer the case. Similarly,
multiple roots in more distal crowns in the jaw are adaptational to
stresses on the crown incurred in lateral bending and torsional effects.
Herbivores, rather than carnivores, have multiple lateral roots;
carnivores first developed the mesiodistal ennumeration of roots due to
rostrocranial tension. But it is perhaps easier to see these as
phylogenetic, but comparative dietary study suggests this is not the case.

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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