(CN) — Unusual footprints made by a limping dinosaur offer yet another link between dinosaurs and modern-day birds.
A group of researchers in Spain studied a fossil trackway and discovered a set of dinosaur footprints made by a bipedal animal that likely stood 20-23 feet tall. One of its feet had an unusually short innermost toe — it was likely injured, according to a study published Wednesday by Carlos M. Herrera-Castillo of the Autonomous University of Madrid and his colleagues in the journal PLOS.
The researchers believe the unknown theropod lived around 129 million years old.
"Walking with an injured leg forces to modify the trot and that is what seems to be observed in these remains: a compensation of the way of walking for an injury to the leg," Herrera-Castillo said in an email.
Birds such as poultry and domestic ostriches suffer a deformity of “crooked toes” or “curled toes". This can be caused by genetics, environmental factors, or lack of certain nutrients in their diet. The sandpiper for example has an abnormal walking pattern to compensate for any injury, much like the unidentified dinosaur, the researchers said in the study.
Despite the despite the size difference and the difficulty of measuring behavior in fossils, this is not the first observed similarity between dinosaurs and modern birds.
"It is known that some dinosaurs took care of their egg layings," Herrera-Castillo said, "some could communicate with sound or visual signals, others had sexual dimorphism (females and males looked different), so it is also expected different reproductive behaviors. The traces of Las Hoyas that we present show us that this theropod corrected its way of walking with a deformed leg in a very similar way to what modern birds would."
The researchers believe the 5-ton dinosaur would have walked on a moist mat that created deep outlines around its toes, putting more pressure on its right foot to accommodate its injury. They plan to recreate the dinosaur’s walking gait to see if there are any other unusual behaviors in how it walked.
While several dinosaurs were found in this ecosystem, this particular dinosaur is twice as large the next largest theropod. Furthermore, Herrera-Castillo says that he and his colleagues "can only speculate" as to why this is the first and only dinosaur of its size and type in the area.
"But we definitely have to keep in mind that Las Hoyas still has a lot to offer," Herrera-Castillo continued. "It is an extremely rich site that is still producing discoveries. Perhaps in the future more footprints will be found, only time will tell".
Research suggests that the dinosaur went through a shallow pool of water, waves subtly flowing against its legs, moving towards the main water source.
All while it walked alone.