Re: Fw: Dinosaurs and birds

[jrc <jrccea@bellsouth.net>]

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

> In any case, the point Jim was trying to make is that the speed of a 
> running (bipedal) animal is largely limited by mechanics of the hind limbs 
> and their interaction with the ground.

Perzackly.....

> Adding thrust from the forelimbs will only add speed if the hind limbs can 
> keep up.  They generally cannot if the animal is already at a sprinting 
> gait, so forelimb-assisted speed increases don't tend to be very feasible 
> for birds.  This is one reason why running birds don't deploy the wings 
> unless they are launching, or engaging in a ground maneuver for which an 
> additional force vector might be helpful in maintaining balance.

Well said.

> That does not rule out maneuverability and balance being enhanced by 
> forelimb dynamics over level terrain, and these will obviously bolster 
> forward progression indirectly.

Yeah.  When my dad was teaching me to play tennis, he spent many hours 
working on how I used my arms and racket to help me maneuver and change 
direction while running (or at least, to minimize their hindrance -- I'm 
pretty much a klutz now, and was then as well).