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Re: Cost in Aquatic Birds (long)
Jaime A. Headden wrote:
> Proposing an aquatic thrust theory for the development of
> aerial mechanics ignores the nature of the appendicular propulsors in
> living vertebrates, which are shorter and stubbier in the adapted forms.
While I agree with Jaime's comments about Archie and the water, I think it
should be pointed out that some adapted forms go for a high aspect ratio in the
water, for some of the same reasons that some species go for a high aspect
the air. This is not inconsistent with the connotation of the words 'shorter'
and 'stubbier' as apparently used in paleontology.
> <In most of today's wing-propelled divers this pressure that keeps them
> from evolving penguin-like flippers is the necessity to be able to fly.
> (Penguins, Great Auks and others have somehow managed do circumvent
> Erm, I think you're taking dippers too far back. They are the exception.
> They also have short, tapered wings.
Aren't they also relatively high aspect ratio (I haven't checked the actual AR)
> Ihe case of the various flying fishes is different, as is that of *Isurus*,
> the mako shark.
Jaime, In what sense is the case of the flying fishes different? I'm not
saying it isn't, I just missed your point. And the example of the mako shark
went right over my head. Can you tell me more about that?
> Auks molt every other feather, retaining the ability to swim during the
> moulting phase.
And some hummingbirds which lose up to 30% of their flight feathers during the
moult also lose up to 30% of their body weight, thereby retaining most of
their flight performance capability, albeit at a substantially reduced
Sounds like pretty similar responses to similar conditions (no need for the
auks to also lose body weight and maintain semi-constant wing loading).
> Quite the opposite, if you read above. The penguin is the not the needed
> plan, it is required for the equitable flying thrust in an aquaeous