Police investigating the discovery of skeletal remains along a riverbank in north Queensland say they believe they are human bones.
A passer-by noticed the bones slightly submerged in sand along the Pioneer River, about 2 kilometres from the Mackay CBD on Friday afternoon.
Senior Sergeant Mark Sweetnam said while the bones were yet to undergo forensic testing, it appeared the remains were part of a human skull.
"They appear to be quite old," he said.
"They're very brittle and very difficult for us to handle."
Police excavated around the site on Saturday.
"We began an investigation to try to determine firstly, are they human remains, and also the origin of those remains," Senior Sergeant Sweetnam said.
"At this stage it's a bit difficult to tell ... there's only bones that have been located, nothing more than that."
Senior Sergeant Sweetnam said forensic testing would be carried out to confirm the remains are human and to determine how long they have been there.
He said it was too early to connect the remains to missing persons cases.
"We'll find out how old they are and if they date back for some time there might not be any need for any further investigation."
He said the bones were unearthed as a result of recent high tides.
"A sand bank has collapsed and the bones have been exposed."
The crime scene will remain established overnight.
Officers have ceased further excavation while the age of the bones is being determined.
