Fossil footprints discovered in Canada show that different dinosaur species sometimes herded together, shedding more light on social interaction among the prehistoric beasts.
The footprints at the Dinosaur Provincial Park in Alberta, Canada, is the first discovery of its kind.
An analysis of the fossil site, detailed in the journal PLOS One, provides the first piece of concrete evidence of mixed species herding behaviour among dinosaurs, similar to how modern wildebeest and zebra travel together on the African plains.
Researchers, including from the University of Reading in the UK, say they were surprised to find fossil tracks of a pair of tyrannosaurs walking side by side and perpendicular to the multi-species herd.
Such multispecies herding could have been a defence strategy against common apex predators like T rexes, the researchers said.
The researchers found 13 horned dinosaur tracks from at least five animals walking side by side on the 30 square meters of the fossil site unearthed so far. They also noticed tracks indicating that an armoured dinosaur like the ankylosaurus walked in the midst of the herd.
The fossil track site, extending into a hillside at the park, also bore the footprint of what may have been a small meat-eating dinosaur.
“I've collected dinosaur bones in Dinosaur Provincial Park for nearly 20 years, but I'd never given footprints much thought. This rim of rock had the look of mud that had been squelched out between your toes and I was immediately intrigued,” Phil Bell, one of the study’s authors from the University of New England, said.
"The tyrannosaur tracks give the sense that they were eyeing up the herd, which is a pretty chilling thought, but we don't know for certain whether they crossed paths.”
The researchers discovered several more track sites within the varied terrain of the park, which they said were still to be properly scrutinised.
“It was incredibly exciting to be walking in the footsteps of dinosaurs 76 million years after they laid them down,” said Brian Pickles, another study author from the University of Reading.
Further digs at the site could unravel more details about how dinosaurs of different species interacted with each other and behaved in their natural environment, Dr Pickles said.
“Dinosaur Park is one of the best-understood dinosaur assemblages globally with more than a century of intense collection and study,” Caleb Brown, another author of the study, said, “but it’s only now that we are getting a sense for its full potential for dinosaur trackways.”
