[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Thoughts on the new Czerkas book (long)



> > On Tuesday, September 10, 2002, at 07:17 AM, Thomas R. Holtz, Jr. wrote:
> >
> > > And the biggy: is this thing a flier? ............. My (admittedly quick)
> > > measurements of the best preserved feathers they show (i.e., ones where
> > > the shaft and the edges are both clearly present) finds an asymmetry of
> > > only 0.9 at best: they assert these feathers are asymmetrical but do not
> show
> > > measurements to back up their case

Why is the assumption often made that lack of assymetry in ancient feathers is a
non-volant indicator?  While it is obvious why modern birds have asymmetric
primaries, I'm sure we are all aware that asymmetry is not necessary for flight,
but simply allows a reduction in shaft mass, and may have developed well after
the origins of flight itself -- as a consequence rather than an enabler.  Tom,
note that I'm not saying that you make that assumption -- this sentence just
triggered the subject in my mind.All the best,
Jim