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Re: Dinosaur Revolution Review

Anthony Docimo <keenir@hotmail.com> wrote:

>  My apologies, then; when I read the statement that modern birds fly around 
> with all sorts of heavy things on their person...I did not think that two 
> tailfeathers (however long they are) qualified as
> ponderously heavy.

No apologies necessary - it's just an hypothesis after all.  At the
very least, the extra-long ribbon-like rectrices of _Confuciusornis_
likely contributed absolutely nothing to flight ability.  Clarke et
al. (2006) suggested that the extra-long wings of _Confuciusornis_
served to compensate for the non-aerodynamic tail.  In living birds
that have aerodynamically costly tails (such as for signalling and
sexual selection) the wings are also proportionally longer to
compensate for the 'draggy' tail.

The long ribbon-like rectrices of _Confuciusornis_ are apparently not
associated with sexual dimorphism, and it's been proposed that they
might have served as an anti-predator device, as deliberate "fright
molt" (Peters and Peters, 2009).  Although many modern birds tend to
have rump feathers that are more loosely attached than the other
feathers, the super-long specialized rectrices of _Confuciusornis_
would seem to be over-engineered if their sole purpose was to be shed.
 Then again, if the predator grabbed the expanded tip of the tail
feather, it would help  _Confuciusornis_ keep its distance from the
predator (about a whole _Confuciusornis_ body length).  If the attack
happened on the ground, then it assumes that the _Confuciusornis_
could outrun the surprised predator, which would be left with a
mouthful of feather while _Confuciusornis_ made tracks or scaled the
nearest tree.  I doubt that _Confuciusornis_ was capable of a
ground-level take-off.