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Re: Fw: Dinosaurs and birds




----- 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).