Here’s the same skull with a preliminary normal map applied:
[sketchfab]6264333df3bd48d09ae1046c1b20bebc[/sketchfab]
Cow Skull by necrophob30 on Sketchfab
This was a quick and dirty bake without a cage, so things within the eye sockets got screwed up in the normal map. But it makes the horns look a lot nicer.