I looking forward to evolve a quadruped to learn how to walk, for that I need a way to measure fitness, therefor I need to measure distance.
I need to get accurate result for the measurement
it doesn't have to be attached to the quadruped it self
Wait until you have it walking before you waste time worrying about measuring distance.
You can always have the quadruped pull a trailer with a measuring wheel.
Or just count the steps.
...R