SAGRAM NOMICAN AIYER
Well, with decomposition, I mentioned as part of the decomposition process, you get skin slipping and you might have the  scalp actually coming away from the skull itself and other times, you might have the skull adhering more, adherent, so to speak to the skull itself.  So it will vary, depending on the nature of the environmental conditions at the time, and any other intervening factors like maybe animal bites, for instance.