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Re: Origin of flight in birds and bats



Jaime Headden <qi_leong@hotmail.com> wrote:

> As an addendum to the second, 
> http://blogs.nature.com/news/2011/11/new_theory_on_bat_flight_has_e.html


“It is a simple but amazing observation that there are no flying
lineages of vertebrates with gliders as a sister group”


Can we say this for certain for birds...?


"...proto-bats, when dropping down from the ceilings of caves, could
use flapping to control their descent and land in the right place to
gobble up prey."


This is *extremely* interesting.  It should be noted however that in a
biological context the distinction between "controlled falling" and
"gliding" is not always clear-cut.  So-called "passive" gliders may
adjust the patagial membrane while airborne - in fact, they must do
this prior to landing.  Flapping (not evident in any extant glider)
represents an extreme expression of movement of the "flight" surface.



Baby partridges also engage in controlled flapping descents (=CFD)
(Jackson et al., 2009; Proc. R. Soc. B 276: 3457–3466).  Because these
chicks use a complete wingstroke during the fall, CFD may not be
appropriate as an incipient flight behavior in proto-birds.






Cheers
Tim