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Re: Phylogeny of Maniraptora
James R. Cunningham <firstname.lastname@example.org> wrote:
Doesn't this make a perhaps unwarranted presumption that passive gliding
precedes active flight?
I said "one gradational pathway for the evolution of active flight"; I
recognize that there are others. Many, many others. The hypothesis that
passive gliding preceded active flight is one possible pathway. "Flapping
start" models represent another pathway.
Why? Perhaps it used the forewings as stationary canards while flapping
with the hindwings?
Yep, I'm not discounting that possibility. But again, using the hindlimbs
for flapping implies a novel method of flight. This model may be
aerodynamically viable, but was it biomechanically possible? And, as you
I only point out that it can't be discounted without investigation, and
insofar as I know -- it hasn't been investigated yet.
I would add that I didn't say that four-winged flying was unlikely; just
that the relatively short arms of _M. gui_, compared to _Archaeopteryx_ and
other birds, and even to some other dromaeosaurids (including taxa that show
no evidence of aerodynamic locomotion) undermines the assertion that its
forelimbs were used as flapping wings in powered flight. Still, I'm happy
to be proved wrong.
Perhaps large (non-vertebrate) dragonflies might be able to partially
address this issue.
As I'm sure you're aware, dragonflies are highly adept fliers. I would add
that multiple pairs of wings does appear to be the primitive condition for
the first flying (pterygote) insects. As arthropods, the first insects also
had the luxury of multiple appendages; vertebrates have to make do with a
maximum of four (five including the tail).
Doesn't this presume that all pterosaurs incorporate the hindlimb into the
Oh no. I did say "may use". I'm aware that at least some pterosaurs had
the flight surface supported only by the forelimbs.
Note that I personally think there were enough pterosaur niches to be
filled and enough pterosaur species filling them that both conditions might
well arise, with the independent condition more likely where yaw authority
issues provided a need.
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