Archaeologists believe they have discovered the world's oldest "calendar" in a field in Scotland.

New analysis of a group of 12 pits excavated in Aberdeenshire shows they appear to mimic the phases of the moon to track lunar months over the course of a year.

The first formal time-measuring devices were previously thought to have been created in Mesopotamia about 5000 years ago.

But the pit alignment, near Crathes Castle, predates those discoveries by thousands of years, experts say.

The Mesolithic monument at Warren Field is said to have been created by hunter-gatherer societies nearly 10,000 years ago.

It was excavated between 2004-06 and recently analysed by a team led by Vince Gaffney, professor of landscape archaeology at the University of Birmingham.

He said: "The evidence suggests that hunter-gatherer societies in Scotland had both the need and sophistication to track time across the years, to correct for seasonal drift of the lunar year and that this occurred nearly 5000 years before the first formal calendars known in the near east."

Dr Richard Bates, from the University of St Andrews, who was also involved in the project, said: "There is no known comparable site in Britain or Europe for several thousands of years after the monument at Warren Fields was constructed," he said.