In Hollywood films, dinosaurs tend to be huge, lumbering armoured beasts – but researchers have uncovered a footprint left by a stegosaurus-like creature no bigger than a cat.
The single footprint was left 100 million years ago in China and is the smallest of its kind ever found, the University of Queensland researchers said.
The little dinosaur may have walked very differently from others in its family, the researchers believe.
Dr Anthony Romilio of the University of Queensland said, “This footprint was made by a herbivorous, armoured dinosaur known broadly as a stegosaur – the family of dinosaurs that includes the famed stegosaurus.
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“Like the stegosaurus, this little dinosaur probably had spikes on its tail and bony plates along its back as an adult.
“With a footprint of less than 6cm, this is the smallest stegosaur footprint known in the world.
“It’s in strong contrast with other stegosaur prints found at the Chinese track site, which measured up to 30cm, and prints found in places like Broome in Western Australia, where they can be up to 80cm.”
The researchers say the footprint is similar to other stegosaurs, with three short, wide, round toe impressions.
But key differences – it's not elongated like larger counterpart prints – suggest the stegosaur may have walked very differently.
Dr Romilio said: “Stegosaurs typically walked with their heels on the ground, much like humans do, but on all fours, which creates long footprints.
“The tiny track shows that this dinosaur had been moving with its heel lifted off the ground, much like a bird or cat does today.
“We’ve only previously seen shortened tracks like this when dinosaurs walked on two legs.”
Associate Professor Lida Xing from the China University of Geosciences (Beijing) said it was possible the dinosaur walked on its toes.
“This could be possible as this is the ancestral condition and a posture of most dinosaurs, but the stegosaur could also have transitioned to heel-walking as it got older,” Dr Xing said.
“A complete set of tracks of these tiny footprints would provide us with the answer to this question, but unfortunately we only have a single footprint.”
Finding the tiny tracks on crowded track sites will be challenging for the researchers.
“The footprints made by tiny armoured dinosaur are much rarer than those formed by other groups of dinosaurs,” Professor Xing said.
“Now that our study has identified nine different dinosaur track sites from this locality, we will look even closer to see if we can find more of these tiny tracks.”
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