Eight centuries of history have shown that some scholars have been found with large piles of stones stuffed in their mouths, something researchers believe locals did to prevent the dead from returning to walk the Earth as zombies.

The research began more than six years ago in what was supposed to be a study of medieval churches in County Roscommon, Ireland.

“One of the discoveries that were found in Ireland with stones dipped in the mouth turning into zombies. Discovery: One of the selections that were found in Ireland with stones dipped in their mouths to prevent them from turning into zombies. He said two male selections, one between 40 and 60 years old, and the other a young adult probably in his twenties, had been found among hundreds of other remains.

“One of them was lying with his head looking up. A large black stone had been deliberately stuffed into his mouth.

“The other one had his head turned to the side and had an even larger rock shoved quite violently into his mouth, so that his jaws were almost dislocated,” he told Discovery News.

“The two men were lying side by side and were discovered together.”

The team first thought they had stumbled upon a Black Death cemetery when the remains of people buried in the late Middle Ages had stones stuck in their mouths because they were involved in vampire-slaying rituals.

Around 3,000 skeletons buried between 700 and 1400 are believed to still be buried at the site.

The belief that zombies cannot return from the grave as the undead has its roots in Haitian culture, where it is linked to voodoo magic and witchcraft.

Superstition is so strong on the Caribbean island that relatives of the dead dismember a corpse so that it cannot return as a zombie. Others will stand guard over a grave to protect the body until decomposition begins.

According to believers, a zombie will rise from its grave in a hypnotic trance, able to respond to stimuli but lacking self-awareness.

Initially, archaeologists believed that the ritual of placing a stone in the mouth could be related to vampire killing, in which a stake is driven into the victim’s heart. Vampires were believed to spread the plague and were thought to place a stone inside their mouth to prevent it. Practitioners also believed that placing a stone in the mouth of a corpse would starve it to death.

In 2009, the remains of a 60-year-old woman with a stone in her mouth were discovered in a 16th-century mass grave on the Venetian island of Lazzaretto Nuovo.

But vampire culture did not evolve until the 16th century, and therefore they cannot explain why stones were found in skeletons dating back to the 8th century.

“In this case, the stones in the mouth could have acted as a barrier to prevent the revenants from returning from their graves,” Dr Read said.

The skeleton of a “vampire” buried in the 16th century has been discovered as a museum exhibit.

Two years ago a collection of bones was discovered in northern Poland that bore the telltale marks of a vampire burial ritual. Experts examined the remains of a man found at the end of an ancient cemetery in the Pomeranian town of Kamiensk.

Now, they have been unveiled as the main attraction at the Kamiensk Earth History Museum, as organizers are preparing an exclusive exhibition just for the vampire. The body was found with a stake stuck in the leg and a small stone in the mouth.

Vampire “experts” said they had placed the stake in the body’s mouth to prevent it from biting or sucking blood from its victims. And the pierced rib and femur, usually with iron spikes, were made to prevent the vampire from emerging from its grave.