Animate bone visibility?

In the outliner I can turn on/off visibility of single bones but these can’t be keyframed.
Is there some other way to animate the visiblitity of single bones?

You can add bones to their own bone layer (Armature / Skeleton panel) and then keyframe the layers on/off

Thank you.

i found there’s a Hide tickbox in the bone tab that can be keyframed so problem solved without bone layers.