A trove of fossilized dinosaur footprints has been found on a slab of rock gathering dust inside an Australian school, scientists said on Wednesday.
The rock went largely unnoticed for 20 years until the school, in Queensland's rural Banana shire, asked paleontologist Anthony Romilio to examine a cluster of three-toed track marks.
Romilio said the slab was stamped with dozens of fossilized footprints dating to the early Jurassic period some 200 million years ago, AFP reported.
It showed "one of the highest concentrations of dinosaur footprints" ever documented in Australia, he said.
"It's an unprecedented snapshot of dinosaur abundance, movement and behavior from a time when no fossilized dinosaur bones have been found in Australia," said Romilio, from the University of Queensland.
"Significant fossils like this can sit unnoticed for years, even in plain sight.
"It's incredible to think that a piece of history this rich was resting in a schoolyard all this time."
Coal miners dug up the slab in 2002 and, noticing the unusual footprints, gifted it to a school in the small town of Biloela, where it was eventually displayed in the foyer.
The rock sat there until researchers started asking around for any dinosaur fossils discovered in the area.
"Some of the teachers thought this was a replica rather than the real thing," Romilio said.
"Everyone didn't quite realize what they actually have.
"They definitely knew it was a dinosaur footprint. But not the level of detail that a researcher like myself would go into."
Romilio said 66 separate track impressions were found on the slab, which had a surface area of less than one square meter.
They belonged to a dinosaur called Anomoepus scambus -- a small and chunky plant eater that walked on two legs, he said.
"Fossilized footprints, even though they are the most abundant of dinosaur fossils, tend to be cast aside by a lot of researchers.
"They don't have the sex appeal of a fossilized bone.
"The vast majority of dinosaur fossils, they're not found by paleontologists. They're actually found by people on the ground."
Romilio's hunt for fossils in the region also unearthed a two-ton boulder marking the entrance to a coal mine car park.
"As I'm driving into the car park, I see one of those car park boulders to stop cars from driving on the lawn.
"And it's got this clear-as-day dinosaur fossil. My jaw dropped when I saw that."
Romilio and a team of researchers published their findings in peer-reviewed journal Historical Biology.
