A GRISLY find on a beach sparked a police investigation.

Officers were drafted in to make a detailed search after a dog walker found part of a human skull, which a hospital consultant considered to be recent.

The grey, dish-shaped bone found on Coatham Beach, Redcar, east Cleveland, had formed the back of the skull of a man who was less than 30 when he died, but tests revealed that he died 5,230 years ago.

Marine growth on the fragment suggested it had been in the sea for some time and experts believe it probably came from an ancient burial ground - possibly a coastal bog burial - which has been eroded by the sea.

Peter Rowe, sites and monuments officer for Tees Archaeology, said the skull bone is an extremely rare find.

He said: "This dates from the Neolithic period when people were just moving away from being hunter-gatherers to growing cereal crops and herding cattle and sheep.

"They would have been using stone axes and flint arrow heads and burying their dead in communal groups.

"This is not an everyday find, we are only talking of perhaps a couple of dozen in the country."

Detective Constable Chris Marchant, of Cleveland Police, said the anthropologist who carbon-dated the find "was able to tell us that there are no signs of any traumatic injury and the bone appears to have become detached from the rest of the skull through natural processes.

"For its age, it is remarkably well preserved, so well in fact a hospital pathologist thought it was quite recent. That resulted in a comprehensive search of the area, but thankfully we are not looking at a suspicious death.

"It is fascinating when you consider how old this piece of bone is. Carbon-dating has pinpointed the age, but the scientist who looked at it was also able to give us the sex and age of the individual."