Tom Read, 15, was searching the River Stour at White Mill, Sturminster Marshall, last June when he found what he initially thought was an old boot.
After discovering the skull, Tom and his mother rightfully contacted the coroners office, who informed the police, who then reached out to the archaeologists.
Forensic archaeologist Paul Cheetham said: “Once we got the skull and looked at it, we realised, it was very dark, stained and blackened. Therefore, it obviously had been in the river, for a very long time and we estimated it had been there for over 100 years.
“The radiocarbon date suggested the skull dated from around about 430 AD to about 600 AD so that’s what we would call the dark ages, just after the Roman period. We don’t have much evidence of what people in Dorset were doing at this time.
“This is a really exciting find and we may be able to follow this up by some excavation work to find out a little bit more about where the skull came from.”
Paul was called to the scene by Dorset police to examine the skull and to decipher if the finding should lead to an investigation.
“Tom showed us exactly where he found it and then, along with the police diving team, we searched the rest of the river and found a number of other bones. All those bones turned out to be animal bones and not suspicious, so the only human remains we did find was the skull fragment that Tom found.”