The fossilised remains of a 23-million-year-old rainforest in the Gold Coast hinterland in Queensland is shining light on a little-understood period of geological history.
The fossils were unearthed from a creek bed by a curious bushwalker and taken to the Queensland Museum for analysis.
Queensland Museum palaeobotanist Dr Andrew Rozefelds said he could not believe his luck that they were brought to him for identification.
Gold Coast Hinterland local Guy Warren was hiking when he found some fragments of rock with leaf impressions at a creek near his home.
He traced the creek upstream to the actual layer where the fossils were coming from, which was sandwiched between layers of volcanic rocks
“I could see that is was quite slatey [sic] so I just broke one of the bits away and then inside that you could see just some perfectly formed leaves,” Mr Warren said.
“I wasn’t looking for fossils, no, just always had my eyes open to see new things.
“I’m fascinated by plants and the bush so I’m always looking out for different things.”
The material is now believed to be from the Miocene Epoch – when Australia had broken away from Antarctica and was starting to drift northwards towards its current position, and northern Australia was covered in lush rainforest.
The discovery has excited Queensland researchers who rarely have access to fossils of this age.
Dr Rozefelds went to the site and came back with a ute full of rock.
He said the discovery is significant as it is one of the few sites from this age found in northern Australia.
“There are earlier records in various publications and they talk about fossil plants being found throughout the Mount Warning volcanic region, but there’s been nothing published on them,” he said.
“It’s the first time that we’ve actually got quite well-preserved material to actually work with.
“We’ve got about six drawers of specimens at this stage.”
Some of the fossils look like eucalyptus leaves
Queensland Museum researchers have identified the fossils as coming from an ancient rainforest.
So far 15 to 20 different leaf types have been discovered, and the team plan to go back to do further field work in the next six months.
Some of the fossilised remains look a lot like eucalyptus leaves.
“It could be just that we’re sampling from different forest types at that time and therefore you’re looking at different forests,” Dr Rozefelds said.
“It could be that eucalyptus occurred with rainforest at that time.”
It had taken a team of volunteers to help Dr Rozefelds to sift through the remains.
Volunteers Desley Faulkner and June Richardson remember well when the fossils were first brought in for analysis.
Mr Faulkner now has the job of doing detailed drawings of the venation or veins of each fossilised leaf, so they can be better identified while Ms Richardson, a retired librarian, catalogues the discoveries.
Dr Rozefelds said it was a great effort of amateurs and professionals working together to shed light on a period of time of which little is known.
“They’ve provided the really important initial work to get this project moving,” he said.