In the age of dinosaurs, some of the biggest living things ever to exist were stomping around Earth leaving footprints as they went. But amongst those mighty trackways are some more modestly sized impressions, like that belonging to a cat-sized baby stegosaur committed to the ground around 100 million years ago. The fun-sized footprint was recently found in China, first stumbled upon by Associate Professor Lida Xing from the China University of Geosciences, Beijing, and published in the journal Palaois.
At just 6 centimeters (2.4 inches) long, it’s the smallest print from a stegosaur (a broad term for the group of dinosaurs that includes stegosaurus) ever found. By comparison, the footprints of adult stegosaurs are a different beast entirely.
“It’s in strong contrast with other stegosaur prints found at the Chinese track site, which measured up to 30 centimeters (1 foot), and prints found in places like Broome in Western Australia where they can be up to 80 centimeters,” said University of Queensland researcher Dr Anthony Romilio in a statement. “Like the stegosaurus, this little dinosaur probably had spikes on its tail and bony plates along its back as an adult.”
An artist’s impression of the stegosaur that accompanied the paper depicts a heartwarming scene of a bug-eyed baby dino looking curiously at a dragonfly. However, the footprint brings more to the table than just the opportunity to coo over a mini stegosaur.
Though the print shares many similarities with other known stegosaurus footprints (three round toe impressions) it differs in a way that is quite perplexing. Stegosaurs were heavy, four-legged dinosaurs that walked with all feet on the ground. This means their prints are preserved with an elongated appearance as their weight shifted over the limb. The baby’s, in comparison, is short, demonstrating it was walking with its heels off the ground a bit like a cat.
“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,” said Xing, who found the print, in a statement. “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 more prints to clarify this will be tricky as the track in China is already crowded and it’s often the smallest feet that get lost among the throng, but the researchers remain hopeful. “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,” concluded Xing.