Re: Origin of feathers

["Norton, Patrick" <Patrick.Norton@state.me.us>]

On 4/23 Dinogeorge wrote:

>Lots of animals are quite agile and capable of overwhelming their prey   
without
needing feathers to do so.<

True. But of course this does nothing to falsify my concept.  Nature   
repeatedly shows us many ways to solve a problem. We know of three very   
different solutions to flight, for example.

>There is nothing compelling about this evolutionary scenario.<

Watch out for circular logic, George. If you assert both your statements   
to be true, then your theory about an aerodynamic-related origin of   
feathers is not a compelling evolutionary scenario either, since other   
animals evolved flight without "needing feathers to do so."

Two other comments on this thread. The first concerns a post of mine   
earlier in March suggesting that the lifestyle of the roadrunner may be   
useful for speculating how flight and feathers may have evolved among   
small cursorial archosaurs. In reviewing the list archives yesterday, I   
realized how unoriginal that idea was. Dr. Richard Cowen, in particular,   
treated a similar concept in much more detail in a series of posts   
beginning on January 9, 1995 under the heading of "feathers and flight."   
His concept also incorporates display as an important factor in the   
evolution of pre-flight feathers; something which sounds abundantly   
reasonable to me.

Finally, it appears that those who accept the   
"parachuting-gliding-flapping" origins of flight need to also explain how   
the ancestors of Archaeopteryx evolved to the flapping stage (however   
limited) with such an inadequate gliding design. Based on measurements   
from a copy of the Berlin specimen of Archeopteryx, I estimate the aspect   
ratio of A's wings at between 2 to 2.5. This is consistent with the   
aspect ratio you get if you measure Paul's silhouette of Archaeopteryx in   
PDW. From an aerodynamic perspective, aspect ratios in that range produce   
a very low lift/drag ratio and therefore a fast sinking rate when   
gliding. Volant birds in that range today compensate for a fast sinking   
rate with powerful flapping.  IMHO, with a fast sinking rate and without   
a powerful compensatory flapping ability, Archeopteryx must have perched   
somewhat precariously.