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Re: What is biomechanics? (or, The Truth About Flying Snakes - Was: Re: science and philosophy)
At 18.19 23/09/02 -0700, you wrote:
Not strictly related to origin of birds but morphology related as well.
I agree that Longisquama was not a glider (contra Haubold and Buffetaut ,
1987), but it may have been a parachuter as an aside effect. I try to
explain better: those elongate appendages perhaps were mainly for
display. However, some drag could have been induced to slow down speed
during falling (a bit more if really they were paired and could have been
spread a little) like the fluffy tail of non-gliding squirrels, it is not a
gliding-parachuting adaptation per se, but works on occasion. Being the
appendages on its back, close to the center of the body, this becomes more
feasible if Longisquama had some device to avoid rotating on its own center
of gravity like maple fruits , . Perhaps an elongate or deep tail might
have helped avoiding this.
Nope ... quite the contrary ... that data I have contradicts it. I
myself never supported it. As I do not support *Longisquama* flying by any
present data. Or even gliding. So far, no study shows what appear to be
radiating slats could even produce a sustained drag or possess a paraxial
resistance to torque that would in anyway resist gravity.
If this was only an aside effect like a safety device for incidental falls
or L. jumped down from tree branches at will I don't know but I would
vote for the first hypothesis.
I know of some references that have drawn differences in animals that
glad versus parachute, and the snake and frog are both considered
parachuters, but presently lack them myself -- I will try to look these
up. The distinction has been to support with anatomy a direction-based
definition, above or below 45 degrees.
one reference about this is
Milton Hildebrand, 1988 Analysis of Vertebrate Structure Third Edition,
Wiley & Sons: at p. 571 he distingushes gliders from parachuters in this way.
All the best
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"Every day men see other men die, they see the chariots with the corpses
and the fires, yet they keep living as they were immortals, this is the
strangest thing of all"
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