In a complete redefinition of the concept of “brave,” an international team of paleontologists has identified the smallest known stegosaurus footprint.
Preserved in stone in the Chinese province of Xinjiang for 100 million years, the print is only 5.7 centimeters (2.24 inches) long and was probably made by a baby stegosaurus (ichnogenus). Deltapodus) about the size of a cat, the research team said.
Fascinatingly, although we do not know the exact species of the small animal, the impression has allowed scientists to infer that stegosaurus babies may have walked differently from adults.
“This footprint was made by a herbivorous, armored dinosaur commonly known as a stegosaurus, the family of dinosaurs that includes the famous stegosaurus,” said paleontologist Anthony Romilio of the University of Queensland in Australia.
“Like the stegosaurus, this small dinosaur probably had spikes on its tail and bone plaques on its back when it was an adult. With a footprint less than six inches, this is the smallest known stegosaurus footprint known in the world.”
The footprint of stegosaurs. (Xing et al., Palaios, 2021)
We know that stegosaurs lived in the region. Dozens of tracks up to 30 inches long have been found, as well as skeletal remains. Elsewhere in the world, the tracks of stegosaurs rarely exceed 50 centimeters.
The footprints of very young stegosaurs and other armored dinosaurs are incredibly rare compared to other species, and it’s not entirely clear why.
It is possible that, living in a herd, many of their footprints were traversed by older, heavier adults, but this does not explain very well how baby footprints of other herds survived. Other explanations include rapid growth: animals may not have been small long enough to leave many footprints; or that nursery habitats were not generally conducive to footprint preservation.
Whatever the reason for the shortage, somehow this only clue survived. The baby’s three-toed foot pressed into the mud; time turned the mud into mud stone, creating a mold that was filled with debris that eventually turned to sandstone, creating a cast of the small step that survived when the mud stone was lost.
While not many details were preserved, the shape of the print was fascinating: it was not as elongated as the footprints of older stegosaurs, the researchers said.
The oldest stegosaurus prints found on the site. (Xing et al., Palaios, 2021)
“Stegosaurs usually walked with their heels on the ground, in the same way that humans do, but on all fours, which creates long footprints,” Romilio said.
“The small footprint shows that this dinosaur had moved with its heel raised off the ground, just as a bird or a cat does today. Only before have we seen shortened tracks like this when dinosaurs walked on two legs.”
This tempting discovery suggests that stegosaurus babies may have moved more lightly and agilely than adults, walking on their toes and passing to the heel as they grow older. Still, with just a single footprint, it’s impossible to say.
The individual stegosaurus that made him might have had a strange way of walking; or maybe he left the weird foot, just for that step.
“A complete set of clues to these small footprints would provide us with the answer to that question,” said paleontologist Lida Xing of China University of Geosciences, who found the impression, “but unfortunately we only have a single footprint.” .
The region where the print was found has yielded nine different dinosaur trail sites; and the specific set that included the baby print also had 16 other older stegosaurus prints. Now that a baby specimen has been found, the team intends to look for clues that can help us answer these fascinating questions in the training.
The research has been published in Palaios.