More than 60 years ago, Bruce Runnegar was visiting Petrie’s Quarry in Brisbane with school friends when he discovered a dinosaur footprint. Measuring 18.5cm in length and set in a small slab of shale, it’s the only dinosaur fossil ever found in Queensland’s capital city.
Now, a new study published in Alcheringa has revealed another amazing discovery: the specimen dates to the start of the Late Triassic period, around 230 million years ago, making it Australia’s oldest known dinosaur fossil.
“At the time, we suspected the marks might be dinosaur tracks, but we couldn’t have imagined their national significance,” says Runnegar, who co-authored the paper. “More than 60 years after we found it, it’s extraordinary to see it recognised as Australia’s oldest dinosaur fossil.”
Researchers believe the track was made by an early sauropodomorph – a small, two-legged, long-necked dinosaur.
“It’s likely the dinosaur was walking through or alongside a waterway when it left the footprint before it was then preserved in sandstone, which was cut millions of years later to construct buildings across Brisbane,” says Anthony Romilio from University of Queensland’s Dinosaur Lab.
Based on its size of the footprint, Romilio estimates the dinosaur was around 78cm tall at the hip and weighed about 144kg. Additional measurements suggest the animal moved at a maximum speed of around 60 km/hour.
“Subsequent urban development has made the original site inaccessible, leaving this footprint as the only surviving dinosaur evidence from the area,” says Romilio, who believes that without Runnegar’s “foresight to preserve this material, Brisbane’s dinosaur history would still be completely unknown.”
Top image: Petrie’s Quarry in Brisbane, 1959. Bruce Runnegar can be seen in the background alongside other students. Credit: Patrick J. Conaghan
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