Dear WW:One of the birds' secrets is the fact that their nerve pathways are relatively short. It takes an appreciable fraction of a second for nerve impulse to travel from brain to an extremity, so small animals can react much sooner than humans can.
I think the big dynasaurs must have had to wait a week for message from brain to reach their hind legs.
Remember the old parlor trick of telling a kid he can have a dollar hung vertically between his thumb and index finger, if he can close them before dollar drops through them? Kids look very much amazed.