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Re: Sifaka and Chukar Behavior: Trees Down or Ground Up?



At 12:47 AM -0800 1/23/03, Jaime A. Headden wrote:

So we now have two possible hypotheses for avian flight orgin, ground up supported by Ken Dial's experiments with galliforms, and trees down supported by Xu et al. on new (and not so new) fossils from the middle Cretaceous of Liaoning. [clipped]

From talking with Ken Dial when I was researching my New Scientist story, I don't know that his findings necessarily support the ground up theory. One point he made is that the little birds used their small wings to flutter back down to the ground after they climbed up an incline. In a more realistic environment, they could be running up a tree or bush, then fluttering back down. The little wings can't lift the birds off the ground, but they could help them come down gently.


If we extrapolate backwards and assume the ancestral forms had similar behavior -- and those are very BIG ifs -- that could mean flight evolved as a short-range behavior to get off the ground and then come back down quickly and efficiently. One thing nobody has mentioned is that some animals which climb up trees have a hard time getting back down, like the classic cat chased up a tree that has to be rescued because it can't get back down. THus wings could have evolved as a temporary escape mechanism that let the proto-birds escape predators, then come back quickly when the predator was gone. -- Jeff Hecht


-- Jeff Hecht, science & technology writer jeff@jeffhecht.com; http://www.jeffhecht.com Boston Correspondent: New Scientist magazine Contributing Editor: Laser Focus World, WDM Solutions 525 Auburn St., Auburndale, MA 02466 USA v. 617-965-3834; fax 617-332-4760