Hey Andy!
Oh, and given all those creatures, I'd definitely say flight evolved from top down.
Every time?
I think that argument can be made where existing limbs have evolved into wings with fair confidence, but I would still hold off on exclusivity.
The discovery of four-winged dinosaurs shows that the glider path may be one of the solutions (see
Error).
But the demonstrated advantage of young grouse to climb trees using wings to augment their legs before they are developed enough for flight shows a "ground up" advantage (see
CNN.com - Dinosaurs' flapping led to flight? - Jan. 18, 2003):
. So these baby birds, born with big feet and big, powerful legs, use them in combination with their wings, first to stay balanced and grounded, and then to take on steeper and steeper inclines. Birds in the turkey and quail families use the same techniques.
Using this "wing assisted incline running," Dial reports in this week's issue of Science magazine that chukar partridges can negotiate 50 degree inclines from the time they are born, 60 degree slopes when they're just four days old, and at 20 days, can perform a vertical ascent with all the skill of Spiderman.
And the use of winglike structures by stoneflies to skim on the surface of water but not to fly also demonstrate a possible path of development for insects where wings did not develop from existing limb structures (see
http://www.rps.psu.edu/student/marden.html}:
Stoneflies spend much of their lives as underwater nymphs, but they must surface and travel to land to mate ... held up by its buoyant feet ... the stonefly is pushed by its whirring wings, like a fan-boat cruising the bayou. Though the stoneflies never engage in true flight -- they don't leave the water surface -- they can reach speeds of 35 centimeters per second (by comparison, a wasp travels at over 100 centimeters per second).
The article has a links that can get you eventually to Jim Marden’s website as well as links directly to videos of this process. You can find out more about Jim from
http://www.bio.psu.edu/People/Faculty/Marden/index.html
Personally I think the diversity of flight mechanism show that a diversity of paths to develop flight is just as possible as the diversity of paths for development of the eye.
Enjoy.
we are limited in our ability to understand
by our ability to understand
Rebel
AAmerican
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[Deist
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