Paintings exhibiting a herd of ceratopsians accompanied by an ankylosaur strolling by way of an previous river channel, watched by two tyrannosaurs
Julius Csotonyi
Did completely different species of plant-eating dinosaurs herd collectively for cover like many fashionable animals do? A set of 76-million-year-old tracks found in Canada is likely to be the primary proof of this – however the case is way from closed.
Final 12 months, Brian Pickles on the College of Studying, UK, and his colleagues found parallel tracks in Dinosaur Provincial Park in Alberta that have been made by at the least 5 particular person animals.
“They’re all subsequent to one another, they usually’re equally spaced,” says Pickles. “So it means that they’re roughly shoulder to shoulder.”
Initially, the researchers thought all of the tracks have been made by ceratopsians, horned dinosaurs such because the well-known Triceratops. They’ll’t make certain precisely which ceratopsid made the tracks, however fossil bones present that species reminiscent of Styracosaurus albertensis have been current within the space on the time.
“As we have been excavating, we realised that one among these units of tracks wasn’t just like the others,” says Pickles. “It’s about the identical measurement, however it’s acquired three toes, and the one giant animals that make footprints like that within the park at the moment are ankylosaurs. So what we’ve got is an ankylosaur in amongst a bunch of ceratopsians.” Ankylosaurs have been closely armoured dinosaurs with club-like tails.
The tracks are thought to have been made close to a river, so the ankylosaur might have been strolling among the many ceraptopsians just because the animals have been all heading to the river to drink on the identical time, he says. However it’s also doable that completely different species of herbivorous dinosaurs herded collectively for longer durations for defence. In reality, the tracks of two predatory tyrannosaurids have been additionally discovered close by.
“In fashionable African ecosystems, giraffes, zebras and wildebeest type these multi-species herds, and a part of that’s to do with completely different species having completely different talents to detect predators,” says Pickles.
Nevertheless, with only a single doable ankylosaur footprint discovered to this point, the case for multi-species herding in dinosaurs isn’t conclusive.
A technician engaged on the tracks at Dinosaur Provincial Park in Alberta, Canada
Dr Brian Pickles, College of Studying
“Given [there were] tracks made by two completely different species of huge, herbivorous dinosaurs in the identical small space, but in addition pointing in the identical course, I’d say that’s tantalising proof they have been herding collectively,” says Anthony Martin at Emory College in Atlanta, Georgia.
“Certain, the ceratopsians and ankylosaur may have moved by way of that place at completely different occasions, however the closeness and spacing of their footprints make for a superb argument that they have been at the least influenced by each other,” he says.
However Anthony Romilio on the College of Queensland, Australia, isn’t satisfied two completely different species made the tracks. “The proposed ceratopsian and ankylosaur tracks look strikingly comparable in form,” he says.
In reality, based mostly on the width of the tracks and the truth that solely hind footprints have been discovered, Romilio suggests they have been in actual fact made by duck-billed dinosaurs. “To my thoughts, these usually tend to be poorly preserved footprints of large-bodied hadrosaurs,” he says.
“This isn’t to say mixed-species teams didn’t happen in dinosaurs. Flocking birds, herding mammals and education fish are all recognized to type mixed-species teams,” says Romilio. “It’s completely believable that some dinosaurs might have achieved the identical.”
Pickles dismisses Romilio’s suggestion concerning the tracks. “They undoubtedly aren’t hadrosaur tracks,” he says.
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