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Re: flying Archie
On Sat, Sep 23, 2006 at 05:43:43PM -0700, T. Michael Keesey scripsit:
> Graydon raises a good point about environmental factors. But, as far
> as we can tell, long-, bony-tailed flying birds went extinct
> everywhere (except Madagascar) by the Late Cretaceous. That's a lot of
> environmental luck. Add to it the fact that bats and pterosaurs have
> parallel development (long-tails giving way to short-tails), and a
> suspicious pattern emerges.
We don't have a statistically significant sample size for bird fossil
locations, do we?
Pterosaurs look like a change in flight mechanics, but also over a mass
Bats, which are small, roost upside down, are frequently nocturnal, and
tend to roost in cold locations, may have an unusual set of selection
pressures about tails just on thermal issues.
I agree that the standard narrative is that the "modern", pygostyle bird
does better than the "archaic", long tailed bird, and even that this
seems inherently plausible, but I don't know of anything that provides
strong support for this view.
> That said, I thought of one other reason short tails would be more
> advantageous: economy. Perhaps both styles of flying are just as
> "good", but the fact that one requires less "equipment" might confer
> an advantage.
Having the extra equipment to exapt might confer advantages, too; one
cannot hang from a limb the tail one doesn't have, and so on.
> (After all, plenty of nonvolant lineages have reduced tails,
> too--e.g., present company.)
Has anyone ever proposed a convincing selective reason for the
tailessness of apes?
> Still, I can't shake the feeling that most modern birds (except for
> those who have secondarily lost the ability) can fly longer, faster,
> and more skillfully than Archie could.
This is much the same thing as saying that T. rex was a more effective
predator than Coelophysis, though -- it's not a comment on the bauplan
so much as a comment on the expected results of inter-bauplan
competition over a long period of time.
If the long-tailed-bird body plan had persisted, we might be marvelling
at the flight efficiency of something that got 60% of its lift from a long,
rigid, tail frond and can do closed-winged controlled diving after fish in