Since when is a cracked skull anyones signature? I used to draw skulls with cracks on my school folder in the 5th grade.
The strikes/cracks have an "S" and a "7" in them. Check out Stomp, Squirm, the Ghost Land stuff, etc., most of them have that zigzag in the design. Secret Base does the same thing by working "S" and "B" into some of their sculpts. (Someone please post pictures, I'm too lazy.)
I always thought the crack or what looked like lightening bolts on the ghost fighter were a nod (or rip) from the bxh kuns.