Re: Fw: Dinosaurs and birds

[jrc <jrccea@bellsouth.net>]

----- Original Message ----- 

> An animal that increases it's maximum speed by generating thrust w/ it's 
> forelimbs as it runs gains an advantage.

An animal that can generate wing forces while running gains a distinct 
advantage, but additional forelimb thrust does not necessarily allow it to 
run faster.  As a visual analogy, imagine yourself running behind a car as 
fast as you can.  Now, attach a rope to the car's bumper and grab the rope 
with your hands.  Have the car accelerate.  You will find that you do not 
gain the ability to run faster; you just go fanny over teakettle.  The 
running advantage is primarily in being able to generate force vectors that 
assist maneuverability. Even ostriches use their wings to that purpose.  It 
seems to me that increasing running speed with wingthrust is more of a 
derived ability than a basal one.
JimC