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Re: EARLY BIRD FROM SPAIN
On Thu, 1 Aug 1996 firstname.lastname@example.org wrote:
> The fossil provides evidence of the oldest known alula or "bastard
> wing,'' Sanz's group wrote in the science journal Nature.
> "The alula is essential in modern birds for low-speed flight and
> manoeuvrability,'' they wrote. The flap of feathers delays stalling
> and is used on take-off and landing.
> The new bird is the earliest one found with an alula. No evidence
> of one has been found in the earliest true birds including
> Archaeopteryx, which indicates they flew clumsily and probably had to
> take off from trees or cliffs.
So we're told that because of lacking the alula birds were both
restricted to and prevented from taking off from trees. Sounds pretty
dubious either way, and the alula may be important, but it seems a little
exaggerated in its importance here. Bats get by fine without them,
insects don't have them, pterosaurs could possibly have approached modern
bird diversity and they don't have them.
Bats, lacking the alula, can land on /take off from the ground.
Vampire bats are one example, some New Zealand bats actually spend much
or most of their time running around on the ground. They can also land in
and take off from the trees (flying foxes) or caves, and I can't think of
any reason to call bats clumsy fliers, and the fact that there are about
1000 species of them or something ridiculous like that proves that
they're good enough at it to suit Mother Nature or natural selection.
Pterosaurs were very diverse, and they didn't have an alula.
There are something like 120 species, I think, which is pretty incredible
considering how poorly they preserve, and probably indicates a very high
diversity. Pteraichnus footprints (Lockley and Hunt reject the crocodile
identification) demonstrate that pterosaurs did spend at least some time
on the ground. Other studies have concluded that some pterosaurs were
best suited to clinging to trees or cliffs, and probably both happened
(although the relative scarcity of Pteraichnus prints might imply they
were less comfortable on the ground, in general).
As for insects- well, they're in a different size category, so
perhaps criticisms don't imply, but I've watched moths hover and fly with
the same agility and energy as any hummingbird, and the insects aren't
doing too poorly.
Certainly, the alula must have played an important role in the
evolution of bird flight, and probably opened up a lot of new
possibilities, perhaps letting birds do things that bats can't and
pterosaurs couldn't, but it sounds like people are jumping to cite this
as evidence for their own views of where birds came from.
So maybe people aren't ignoring Greg Paul, just
good sense and good science ;).