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Re: MY THOUGHTS ON THE 'DINO/BIRDS'
>You may be right with Caudipteryx, its tail is rather similiar to the
>some of the fan tails found in colies and some "piciformes" (and
>Sandcoleiformes) that might be for display. However, nothing says that
>the tail didn't bear a slight aerodynamic function perhaps related to
True enough - of course no living bird has a long flexible tail. I wonder how
rigid the tail of Caudipteryx was? I still find it hard to believe that
short-winged creature could have flown or glided (though Protarchaeopteryx
might have done, I suppose). I am not familiar with the Sancoleiformes - a
fossil taxon, I presume?
>I still cannot find any logic within the "fluttering" model that was
>made by Caple et al.. I go along with Rayner (1991) who says:
Do you have the reference for Caple? Gee, someone else thought of this
>"...are implausible, for two reasons. First, there are no comtemporary
>analogues of running animals feeding with their wings, or using
>forelimbs as lifting surfaces for stability: running birds generally
>fold their wings to minimize drag.
If this refers to the "insect-net" idea, I agree it is nonsense. Of course
some birds do use their wings in foraging (eg the Black Heron). Again, I fail
to see what this has to do with the idea of an upward leap from a standing
(rather than a running) position accompanied by a flutter (as in grouse or
cranes, for example).
Second, and more important, neither
>model addresses the question of *why* the wings should be flapped, and
>how imprecise forms of wing waving needed for predation or stability
>developed into true flapping...
I have not done this, of course, but I have suggested here that any extension
of a leap, or slowing of a fall back, could be of use in getting at prey
slightly out of reach of "mere" leapers, or in making a display leap more
striking. Thus even a slight development in that direction could be
>yet the first "flights" of a fluttering proto-flapper would have been at
>low speeds, where the energetic demands of flight are at their most
>extreme (Clark 1977), and the wingbeat cycle is at its most complex
>(Rayner 1988a,b). This model need not be considered further."
This again assumes that the function of proto-flapping was to get from point A
to point B. This need not have been the case; many flycatching birds
their original perch after an aerial foray, and displaying leapers are only
trying to show off, not to get anywhere. Under such circumstances I don't
think much in the way of aerodynamic stability need to have been involved.
This is why he
>supported the hypothesis that flight in birds evolved when theropods ran
>and jumped into the wind. This fails because it assumes that wind would
>be constant and that early birds did not the have the special anatomical
>controls that modern birds had.
Again - this is NOT what I am suggesting (and bear in mind I am not
be any more than an armchair quarterback here!)
Ronald I. Orenstein Phone: (905) 820-7886
International Wildlife Coalition Fax/Modem: (905) 569-0116
1825 Shady Creek Court
Mississauga, Ontario, Canada L5L 3W2 mailto:firstname.lastname@example.org