Archaeologists have found the skull of an ancient Roman who was killed while trying to flee Pompeii as it was engulfed by the eruption of Mount Vesuvius 2,000 years ago.

The skull was found with the jaw agape, frozen in an expression of fear and horror.

“His mouth is open wide, in a very striking manner,” said Massimo Osanna, the director of the archaeological site, which lies south of Naples.

The rest of the man’s body was discovered last month beneath a large stone slab and it was originally thought he died from being decapitated as the rock was hurled through the air by the force of the volcanic blast.

With the discovery of his skull, however, experts now believe that the man died from being suffocated by the volcanic ash that rained down on the bustling Roman town in AD 79, rather than being squashed by the rock.