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RE: Campbell's even crazier than a MANIAC? (archeopteryx climbing)
> > OTOH, these arboreal characters are exaptations in
> most living gliders. Flying squirrels are perhaps most
> adapted, but *Draco* and colugos really just expanded on a
> pre-existing theme.
> I'm not sure what you mean here.
"These" -> "the above". The living parachuters/gliders that are compared with
Archie are all derived from splay-legged animals anyway, with flying squirrels
perhaps being the most derived as regards posture/limb/shoulder/pelvic anatomy.
So given that *Draco*, colugos and flying frogs are derived from ancestors with
the correct anatomy for their mode of climbing, it is obvious that they would
expand on it as they did, and as we *know* to be a good way towards a very
This *would not* be the way Archie would have struggled up a vertical early or
pre-spermatophyte (-> non-branching) trunk say 5 ft high. Such a structure it
definitely *could* have used as a lookout and "perch" (except it would really
stand atop the fronds/leaves, not perch on branches). That much we can tell -
it was neither adapted to sprawl-limbed climbing, nor would that be terribly
efficient to get up . A running jump and a few lunges with the hand claws would
to the trick better.
And a perch of that height was all it needed to give its flight capability a
definite and massive edge. It could swoop dowen on prey and keep an eye out for
predators. And there were no colugos and flying squirrels and tree kangaroos
and birds and other competitors, while parachuting lizards and frogs would
better *not* have shared a trunk with Archie for their own good.
There is really no analogue among modern birds, but seriemas might compare as
regards the use of any higher-up site as lookout and launch site.
As soon as Archie was more than 3-4 ft above ground, it *would* have been
technically able to fly for dozens, perhaps hundreds of meters in most cases.
That we also can tell. A free-standing launch site also allows to make best use
of the wind. In such a situation, Archie's flight ability would be most
efficiently exploited. But did it encounter sufficient elevated spots and would
it have found it easy enough to get up there?
Modern weak-flying landbirds - especially Galliformes - often use a kind of
catapult launch, running to speed and only then pushing off and beating.
Beating with all they got. One can see it when "flushing" a quail, pheasant,
partridge etc; they accelerate with little or no wing involvement (it's
pointless when you are not on open ground but in grass cover) and then burst up
into the air. From raw power output, Archie could have done it maybe, but from
its shoulder girdle - without a hypertrophied sternum and as it seems without a
rotated scapula -, I am unsure. The real problem with the cursorial hypothesis
is not take-off, but to get more than a foot (the actual animal's foot) or so
off the ground, and *not* bounce into an invisible ceiling and go down again
after 2-5 meters.
Perhaps it would be worthwhile to get more geologists and geographers
interested in the topic and hear what they can find out about the habitat both
at the micro and the macro scales. Because IIRC, no Archie fossil has actually
been found in a terrestrial sediment, so its precise range is unknown except
that it must have been not too far from the lagoon or the carcasses would have
become more disarticulated.
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