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Re: Screaming dromaeosaur biplane killers of the air



Greg Paul (GSP1954@aol.com) wrote:

<Steve Czerkas was correct that the Johel dromaeosaurs have fully
developed arm wings. At the same time it turns out they had fully
developed leg wing too.>

  Czerckas' ascription of a full wing to *Cryptovolans* was based on the
assumption that the feathers in the type and paratype skeletons found
running perpendicular to the metatarsus were in fact from the arm. This
protracted his estimate of a wing length. The actual wing feathers are, as
shown in the type and in *Microraptor gui,* fairly short, with the longest
wing feather shorter than the bony arm (I wrote on this before).


> 
<The life restoration of the biplane dromaeosaurs with protflier type
narrow inner arm and leg wings is incorrect, the inner wing feathers are 
as long, and the wings therefore as broad in chord, as in modern birds.>

  In the type of *M. gui*, the longest preserved secondary is almost a
third the length of the longest primary, rejecting this statement. The
aspect ratio is thus 5.77. This is similar to birds with soaring or
speed-adapted wings, not what you would expect in such a primitive flier.
Rather, very short secondaries appear consistent with the other
maniraptorans which have partial wings but do not seem to be able to fly
(e.g., *Caudipteryx*). Rather than posit a regressive wing design to
flightlessness, an elegant theory, it is just as likely given the same
data that the reverse is true and the wings were not used for flight but
rather, as Scott Hartman presented in 2001, to aid in aerodynamic control
during chases. This also fits into Dial's hypothesis, a theory that does
not seem to find favor in the quoted post.

  There is also a problem with the use of a biplane analogy: biplanes have
two foils, one above the other, rather than a foil behind the other, one
which has a narrower, broader curved design than the wing itself. The butt
fans [ :) ] also seem to have been much less than horizontal, given the
lack of a lateral extension of the femur in *Microraptor* (see previous
post in this thread).

<In no way are the Johel sinornithosaurs (incl microraptors) mere gliders
that retained the ancestoral dino-avian protoflight condition into the
Cretaceous.>

  One might want to be a bit more theoretical in this statement.

<In absolutely no respect are the sinornithosaurs less well adapted for
flight than Arch, and no evidence has been presented that shows they
were.>

  Indeed, no evidence. Such as the advanced acrocoracoid process, reflexed
coracoid behind the vertical, larger arms, shorter caudal count, more
avian skull design ... in retrospect, the "sinornithosaurus" (really, just
*Microraptor gui*) has a very large sternum, more than three uncinate
processes, longest rib is well posterior to the middle trunk at distal
extent on the fore-aft direction, but are faulted on the arm and leg
design. *Archaeopteryx* has a more avian tarsus and foot, with a reversed
hallux and 

<In many respects they are obviously much better adapted fliers. Indeed,
the sinornithosaurs approached cunfuciusornids and basal pterosaurs in
flight adaptations.  Basal dromaeosaurs were early powered fliers that
either show what was going on after the Arch grade, and/or represent a
sideline, they do not tell us what was going on before Arch flight grade
and using them for this purpose is very misleading.>

  How so? Is this based on mapping the features to an assumption of
*Archaeopteryx* occuring before the so-called more basal dromies, in an
attempt to resolve the temporal paradox? This doesn't stop the
mammologists who have the older marsupials in the fossil record before the
oldest monotremes appear. As for flight adaptations, *Archaeopteryx* was
likely the better flier in having a longer arm, broad primary fan, longer
primaries than arms, a shorter trunk and shorter hindlegs with a
specialized, lighter skull, a more advanced humeral elevator system and
incipient triosseal canal with a taller and more proximal acrocoracoid,
less-fixed coracoid to scapulocoracoid, and more prominent acromial
process with rounded, U-shaped furcula, as in more advanced birds. Unless
they, too, are subject to the paradox. Confuciusornithids are further
advanced in the form of the scapulocoracopid, robusticity of the arms and
anatomy of the manus and carpus, size of the feathered wing, reduction of
the tail and legs, shortness and depth of the trunk and brevity of the
pelvis.

  This is not based on a preconception of *Archaeopteryx* as an advanced
protobird or early bird that is just earlier in time.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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