You can’t think of how an animal would have wheels?
It doesn’t make me think of replacing animals’ legs, but rather a dog pushing a wheelbarrow.
Or, if you’re wanting an animal with wheels for legs:
Picture that you’re holding a bar of soap in your hand, and you squeeze the soap, it flies forward, and proceeds to hit you in the eye.
Using that thought, picture this:
A wheel on a rotating axis, with small triangles on the flat sides, arranged in such a way that the triangles form a circle of triangles around the flat sides. when a bar/bone/whatever pushes against the triangles on either sides of the wheel, then it pushes the wheel around.
There’s millions of examples of muscles that could push the bone/bar back & forward against the triangles on the side of the wheel, eg the heart.
Perhaps even triangles closer to the centre of the wheel for higher gears, and triangles closer to the outer edge of the wheel for lower gears.
Or even a huge ridge from the outer edge to the center, for an entire spectrum of gears.
Or For a diagram (thanks to mspaint) go to:
Well, have a most excellent day, and party on…