Paleontologist Anthony Romilio brushes a roughly 200 million year old boulder at Biloela State High School in Queensland, Australia. (University of Queensland)
For two decades, Australian students walked by the 5-foot-long boulder in their school’s foyer unaware of its significance. When paleontologist Anthony Romilio finally inspected the roughly 200 million year old artifact in 2023, he had to remove a few pieces of chewed gum stuck to the sandstone before he could take a closer look.
“I was skeptical, you might say, because it’s usually not the place where you look [for fossils],” Romilio said of schools.
But Romilio found 66 dinosaur footprints on the boulder, which is about 10 square feet, marking one of the highest concentrations of dinosaur footprints ever documented in Australia, he said in a study published this month in the Historical Biology journal. Forty-seven dinosaurs stepped on the boulder, which was covered by shallow water, during their lifetimes, offering insight into dinosaurs during the Early Jurassic age, a period from which no dinosaur bones have been found in Australia, Romilio said.
Geologist Wes Nichols discovered the boulder in the Callide Mine in Queensland, Australia, in the early 2000s. Miners have to cut through rock to access coal, and in the past few decades, rocks from the mine have been found to trace back to between 174 and 202 million years ago.
Nichols donated the boulder to his wife, Di, who taught science at nearby Biloela State High School, which serves about 550 students between gradesseven and 12. A few footprints that appeared to be from dinosaurs were visible on the boulder, but nobody knew their significance.
In 2002, the school placed the roughly 330-pound boulder on a stand in its foyer, where students at the time painted a mural of dinosaurs on the walls, including a triceratops and a Tyrannosaurus rex.
Many students and teachers pass the boulder while walking into the building or outside toward the school’s playground. The room is connected to the main office, so students wait there to meet with administrators.
“The specimen had been just sitting so innocuously, you know, in our foyer for so long, it’s just become a part of where we work,” Biloela State deputy principal David Hall said. “We see it every day.”
After Romilio revealed in 2020 that he had discovered dinosaur footprints at a separate cave in Queensland, he heard from citizen scientists, ordinary people who use their basic understanding of science to conduct research and help professional scientists. They told him there was a boulder at Biloela State worth inspecting, Romilio said.
Romilio said he first drove about 400 miles to the high school in 2021, when he saw the outline of dinosaur footprints on the boulder. But he couldn’t lift the rock to examine it.
Romilio said his other dinosaur research prevented him from returning to the school until 2023, when two plumbers lifted the boulder and placed it on a sofa cushion on the floor. Wearing gloves, Romilio removed gum and brushed off dirt.
He covered the boulder with a pink silicone that copied the surface and took photos of the boulder to take home. There, Romilio used 3D imaging and light filters on the photos to highlight shadows on the boulder. That made dozens of three-toed footprints stand out.
“Oh my gosh, there’s so many here,” Romilio, 55, recalled thinking.
Most of the footprints were between three and five inches long, and they appeared to be heading in different directions. Romilio said the dinosaurs might have been crossing a river.
Researchers determined the footprints belonged to the ichnospecies Anomoepus scambus. No bones for the possible species have been discovered, but paleontologists used fossilized traces — footprints and trackways — to determine the animal was probably a small, three-toed herbivore.
While Biloela State students are excited about the rock’s newfound backstory, Hall, the deputy principal, said he’s looking to move the boulder to a nearby public viewing area.
“Maybe in a more protected area,” he said, “rather than in a student foyer.”