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Re: 11th specimen of Archaeopteryx



(meant to send this to the list...)

Sure, some things are more uncertain than others. But which of these
hypotheses concerning the possible asymmetrical remige functionality
is currently better supported by evidence?

1) Lift generation for arboreal assistance (WAIR, or something similar)
2) Aiding in turning while running

How many studies have been done on the role of asymmetry in each function?

Scott Hartman wrote:
"And finally, asymmetrical feathers are in no way directly linked to an
arboreal lifestyle."

I never said they were. But the proponents of the arboreal lifestyle
are the only ones with a wealth of studies and research on their side.
There are plenty of papers discussing WAIR. I'd be curious to read
those for turning, especially since in modern birds, even those that
use their wings for turning, the feathers are not aerodynamic, and
there was apparently no selective pressure to retain asymmetry for
this purpose. If we're doing science, when there are two competing
hypotheses, one backed up by current studies (WAIR) and one not
(turning), the response should not be "well, we have no idea what they
were for." The response should be "current research suggests WAIR is a
likely use for asymmetrical feathers while alternate hypotheses
require more investigation."

As Mike said above, there is no evidence to suggest that asymmetry was
the ancestral condition, and in fact there's evidence against it
unless you consider caudipterids and Sinornithosaurus to be
secondarily flightless.

What gets me is that people keep citing "lack of arboreal features",
while discounting feather asymmetry as one, despite the fact that no
alternate interpretations of that character have been seriously
investigated. If Archie had symmetrical feathers but a reversed
hallux, it would be just as easy to say that the hallux is not an
arboreal feature and that it would be possible to think up alternate
uses for it, so therefore Archie has no arboreal features. "The
asymmetry is not an arboreal feature because Archie has no other
arboreal features" does not strike me as a very sound
counter-argument.

Matt

On Mon, Oct 24, 2011 at 1:54 PM, Mike Keesey <keesey@gmail.com> wrote:
> On Mon, Oct 24, 2011 at 10:51 AM, Matthew Martyniuk <martyniuk@gmail.com> 
> wrote:
>>
>> We need to learn a lesson from the BANDits; it's not enough to shoot
>> down a hypothesis without proposing any alternative.
>
> On the other hand, there are cases where we have to admit, "We don't
> know [yet]."
>
> --
> T. Michael Keesey
> http://tmkeesey.net/
>