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Re: four winged Archaeopteryx
Richard Cowen wrote:
In my biased view, the other signs that Archaeopteryx flew weakly or not
at all make up a more parsimonious picture of A as a ground-running
displaying feathered little theropod than any of the alternatives.
This is throwing the baby out with the bathwater. I think we can say with
a high degree of confidence that _Archaeopteryx_ was not a superb flier; but
to say that it was a completely ground-dwelling theropod with the remiges
and rectrices used solely for display is going *way* too far, IMHO.
My remark about the tail of Archaeopteryx came from Balmford, A. et al.
1993. Aerodynamics and the evolution of long tails in birds. Nature 361:
628-631. The bottom line from that paper was that Archaeopteryx type tails
make flight worse, not better.
Ummm.... no. Baldwin et al. (1993) were looking at tail elongation in
*modern* species species, and examining its effects on aerodynamics. No
modern bird has an "_Archaeopteryx_-type tail", just as no modern bird has
an _Archaeopteryx_-like body plan. It is not helpful to extrapolate tail
length in modern birds to tail length in _Archaeopteryx_, given that the
flight mechanics of early birds were very different to modern birds. The
long tail and "rectricial frond" of _Archaeopteryx_ may have served a
purpose in aerial locomotion, in a manner that has no modern analog. These
issues have been discussed at length in papers by Gatesy, Dial, Hutchinson,
[Therefore I would argue that that tail was selected less for flight than
for display, or ground maneuvering.]
As well as _Archaeopteryx_, a long tail is also seen in other Mesozoic birds
(e.g., _Rahonavis_, _Jeholornis_/_Shenzhouraptor, _Yandangornis_,
_Dalianraptor_). Some of these birds show improved flight capabilities
compared to _Archaeopteryx_, suggesting that a long tail is not an
impediment to flight. One view is that the long bony tail was integral to
an early experimentation in flight where the tail played a greater role than
in modern birds.