Apparently he moves on all 4 legs to maintain the balance? The backlesg are really weak (both in skeleton structure and -- how is this in english? - homing engine - he definitely can't jump properly which is a shame since basic concept kinda implies).
hey, thanks for the comment, the skeletal structure is not meant to show the mechanics of the design, or show how it works, its just meant to help the person who is trying to model this, and also animate it. more of a basic joint break down for which way each one is intended to move.