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Re: 11th specimen of Archaeopteryx



On 10/24/2011 1:51 PM, Matthew Martyniuk wrote:

This boils down to "well, there may be some other explanation other
than arboreality we don't know about yet." That may be true. But are
there any studies that propose what that may be? Off the top of my
head I recall that wings have been proposed as functioning in
maneuverability during fast running. Do asymmetrical remiges aid this?
Any studies on the topic? Have any alternate functions of feather
asymmetry ever been proposed and researched? If not, how does this
refute the arboreality hypothesis? We already know that modern birds
use such feathers to get into high places and/or fly, and it's
unlikely Archie was doing the later.

WAIR, shmair.

Putting a safety-seeking diurnal ground-foraging feathered biped into a tree at night is a good way to evolve an Archie-style body -- not because they must evolve wings to get up into the tree, but rather because wings, asymmetrical remiges and passive flight capabilities are advantageous when getting down to the ground the next morning. Or even that night, should the safe tree suddenly become not so safe.

Of the many alternatives suggested I prefer the ground-foraging tree-rooster (GFTR) lifestyle for creating Archie-type bodies because it (and only it, in my view) explains fully 1) the wing-claws, essential for the rudimentary climbing skills needed to access the roost (and the attendant potential energy necessary to evolve passive flight), 2) asymmetrical remiges, 3) limited wing upstroke, 4) obvious running ability and 5) weak or non-existent keel.

Imagine an evil professor has placed your persona in an Archie body and sent you back to the Mesozoic just before sundown -- your 1st concern is surviving the night, and finding an easy tree to get into is an alternative, as engineering skills are useless when you have no hands.

When the sunrises the next morning, you will be hungry -- should you spy a careless bite-size critter on the ground below, gliding or parachuting down is certainly more likely to result in a meal than trying to clamber down. So you thank your lucky stars you are not arboreal, and give it a go.

If you miss the creature, or are still hungry, then it is time to use those long legs to find and catch another mouthful. Again you grateful to not be arboreal, but rather cursorial. When the day is done, then time to clamber up up into bed. So what if you are not optimized for climbing? It ain't like you are going to stay there all day.

GFTR is a viable lifestyle, and provides a seamless incremental theoretical path from feathered (symmetrical or not) cursorial biped all the way to full flight. As such, I think it is under-appreciated.

We need to learn a lesson from the BANDits; it's not enough to shoot
down a hypothesis without proposing any alternative.

Nah, that's OK -- we will probably never know, and it is even a stretch in my view to call the various scenarios hypotheses.

If too much is
made of feather asymmetry, it's only because few people have proposed
or been able to support any alternate hypotheses.

Agreed.