Richard Cowen (cowen@blueoakfarm.com) wrote:
<Nick Longrich says he sees "flight feathers" (his words) on
Archaeopteryx and
he infers that it was "four-winged" (his words). However, his whole
interpretative construct depends on his assumption that
Archaeopteryx flew
pretty well, and as I've argued too many times, that's highly
unlikely.
Archaeopteryx could not lift its arms above horizontal; it did not
have the
supracoracoideus structure in the shoulder; the furcula is rigid
rather than
flexible; the long bony tail provides a huge amount of drag rather
than lift;
the ends of the forelimbs have clawed fingers rather than primary
feathers;
etc. etc. Those feathers on the hind limbs could have been for
display, or
for aerodynamic turning in an agile runner and hunter. Longrich
documents
*aerodynamic* feathers which may or may not be "flight feathers", and
"four-winged" is so prejudicial a term that it should be struck
from any
manuscript. Obviously, this question is going to go on and on until
there's a
resolution We still lack a full analysis, and it may have to wait
for some new
fossils. Meanwhile, we should go with as uniformitarian an
interpretation as
possible: and that says that Archaeopteryx was NOT four-winged."
I agree with some points made in this post, but I cannot agree
with the main
premise: It is true that *Archaeopteryx* lacked the structure found
in modern
birds and even available to bats and pterosaurs that are productive
to powered
flight and the fully developed flight stroke, but it is not
actually neccessary
— unless these features are defined as neccessary for "flight" to
exist — for
these features to be present and that a vertebrate such as
*Archaeopteryx*
"flew". There is considerable data suggesting that flight preceded
"powered"
flight, and that there were aerodynamic and possible "soaring"
features present
before the advent of the features Richard Cowen listed above (which
occured
WITHIN and not AT the origin of birds) that are conducive to
producing lift and
aerodynamic control while the animal is in the air (or running on
the ground,
or running up trees, etc.).
I also disagree with Longrich's point that *Archaeopteryx* should
be the
focus of origin of flight in birds, since it's apparently likely
that flight or
its prerequisites, evolved before the entity "Aves" or even "birds"
likely
existed.
Cheers,
Jaime A. Headden
http://bitestuff.blogspot.com/
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
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