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Re: Ornithurine diversity
Tail morphology does affect launch performance, but it is not the
primary feature associated with burst launch in animals like pigeons
and doves. Some of the more critical burst-launch characteristics
include: large pectoralis muscle fraction (esp. pec. minor), improved
elevation arc of the forelimb, rapid starting vortex production via
wing stroke alterations (clap and fling, AP wing "slicing", etc),
altered preload phase with a more vertical push from the hind limbs,
and overall reinforced skeletal spar (the proximal forelimbs,
especially, are subjected to higher-than-average loads).
In any case, those skeletomuscular features might be a better place to
look for evidence of vertical burst launch in Mesozoic birds (not that
tail morph analysis isn't important, too). As for the advantages, I
agree with John's assessment - it has substantial anti-predation
On Saturday, July 12, 2008, at 02:49 PM, john bois wrote:
...even the apparent lack of a proper fanning tail (unknown in
enantis this far) might be considered, though I really have no idea
how that should help to survive...
If I understand the question properly...a fanning tail is an aid to
vertical lift-off. Pigeons (for example) have an amazing capacity for
getting high raipdly (hippies take note!). Just quickly, this could
aid survival in the following ways: terrestrial (and even aerial)
predators have to get closer to affect a catch--this means that a
pigeon can react more slowly, eat for a longer period of time, before
having to fly off; such birds can also take advantage of food that is
in places that have ambush predators...because they can lift off more
quickly they can escape predators that would catch fanless birds.
Either or both of these could grant fanned birds more time at feeding
sites...so, not only could they feed longer they could live longer.
Michael Habib, M.S.
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280 0181