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Re: Lemurs and Feathers
> In a message dated 6/19/01 2:44:01 PM, firstname.lastname@example.org writes:
> << Underwater flight provides a scenario in which the flapping movement
> the aero-/hydrodynamic wing shape etc.) can be perfected >>
> The problem with underwater flight is lack of fossil evidence.
I'll ignore that, like everyone else does :-> , given that the Jurassic
fossil record of pretty much all small terrestrial animals is extremely
> progression from non-avian to avian forelimb occurred in animals that ALL
> long thin hind limbs. They were not swimmers (other than when forced to,
> perhaps) -- they were born to run.
IMHO all were capable of running, and swimming was not done with the legs.
> <<flight in air is apparently next to impossible with symmetrical and
> asymmetrical wing feathers>>
> So some people say.
&§&%§&%§?$&§§%. It was nearly midnight when I wrote that. Once more: "flight
in air is apparently next to impossible with symmetrical wing feathers".
> Here's a hypothesis: ALL fossilized dinofeathers have SOME degree of
> asymmetry. Hard to disprove, right? Poorly preserved, right? Ever plucked
> chicken? There's hardly a symmetrical feather on it. Why assume
> started out symmetrical? Their scales already weren't. Most integumentary
> structures in nature are quite asymmetrical, including scales, scutes,
> feathers, claws, teeth . . . um, have I missed any? The accusation of
> theropods having symmetrical feathers seems likely to fade away with the
> first specimen preserved well enough to give clear measurements of such
Here's another hypothesis. All recent flightless birds have symmetrical
feathers, right? (In ancient Egypt ostriches were the symbol of justice
because their wing feathers are perfectly symmetrical.) Same for
*Caudipteryx*, right? This seems to imply that if there's no selectionary
pressure favoring asymmetry, wing feathers become symmetrical.
I don't talk of millimeters here.
> Based on a simple look around the animal kingdom, why not go with the
> majority? Asymmetry is plesiomorphic for MOST vertebrate structures,
The keeled scales of snakes are symmetrical... lots of dinosaur osteoderms
are symmetrical... lots of vertebrate structures are. Statistics is IMHO a
poor argument here.
But that's irrelevant to start with!!! :-) Should wing feathers, for
whatever reason, have been asymmetrical like those of flying birds incl.
*Archaeopteryx*, then I need not explain how this evolved, and underwater
flight could have been easier from the beginning.