Origin of the phrase: Youd lose your head if it wasnt attached.
It's possible that P.O.E. is onto something. :^)
In Britain before the Romans, separate burial of the severed head of the deceased was practiced for higher status people. The practice may or may not have been commonplace (there aren't all that many human remains that old in Britain) but it is referenced in the Welsh Mabinogeon. The head of Bran the Blessed (not Brian the Blessed, I'm onto ya) was cut off and buried in the east, facing Europe, to protect the island from invasion. It didn't work though. ;^)
I saw similar internment caverns under a monastery in Jerusalem. It dated back to the 6th century and probably was adapted to Roman custom. Rumor has it that several monasteries had burial catacombs like the one I personally observed, although I only saw the one.