Re: Cost in Aquatic Birds (long)

["James R. Cunningham" <jrccea@bellsouth.net>]

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 
ratio in
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
> this.)>
>
>   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 
efficiency.
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
> environment.

Yeah.