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Re: four winged Archaeopteryx
The supracoracoideus was experimentally disconnected in pigeons, but
they did NOT fly just fine.
This was an experiment done in Nazi-era Germany by Max-Heinz Sy (1936,
Actually, I think that Jim is referring to the more recent work.
Degernes and Feduccia (2001) cut the tendon of the supracoracoideus
muscle of pigeons and cockatiels, for example.
They remark that "None of the birds undergoing unilateral or bilateral
tenectomy had normal dorsal extension of the affected wing, but each
was able to fly well enough to escape if taken outdoors. We concluded
that neither unilateral nor bilateral supracoracoideus tenectomy is an
effective technique for deflighting cockatiels or pigeons."
I believe that have been some other recent studies with similar
results. Note as well that pigeons are something of an extreme case:
they are largely burst launching species with a very large
supracoracoideus. So they stand to lose the most from such a
tenectomy. The same procedure in other species would probably have
even less impact.
If a bird or an airplane has to avoid flying in "slower speed
ranges", it can't take off.
This turns out not to be the case, actually. Plenty of modern birds
must avoid slower speed ranges because they cannot avoid stall at low
speeds. They compensate in various ways, a running launch being one.
Of course, it is quite unlikely that Archaeopteryx would even need
that. I suspect it could hit steady state from a leaping launch (like
nearly all modern birds that are semi-terrestrial with low wing
loadings). Even if it could not get in especially rapid or powerful
strokes, Archaeopteryx would have been able to get far enough to make
such short flights of benefit for predator escape. If it had any sort
of elevated launch point, then it could get very far indeed, even
without any flight stroke at all.
We should also be careful assuming that the deltoids would be as
ineffective in an early flying bird as in modern ones. The deltoid is
likely somewhat reduced in neornithines because the supracoracoideus
has the dominant role in the upstroke (thereby making deltoid elevation
largely redundant). In earlier lineages, without an elevation
supracora., it stands to reason that the deltoid could be more
powerful, so we must not extrapolate too much (as tempting as that can