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 defense like many trendy animals do? A set of 76-million-year-old tracks found in Canada is perhaps the primary proof of this – however the case is way from closed.
Final yr, Brian Pickles on the College of Studying, UK, and his colleagues found parallel tracks in Dinosaur Provincial Park in Alberta that had been made by no less than 5 particular person animals.
“They’re all subsequent to one another, and so they’re equally spaced,” says Pickles. “So it means that they’re roughly shoulder to shoulder.”
Initially, the researchers thought all of the tracks had been made by ceratopsians, horned dinosaurs such because the well-known Triceratops. They will’t ensure precisely which ceratopsid made the tracks, however fossil bones present that species corresponding to Styracosaurus albertensis had been current within the space on the time.
“As we had been excavating, we realised that considered one of these units of tracks wasn’t just like the others,” says Pickles. “It’s about the identical measurement, but it surely’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 is an ankylosaur in amongst a bunch of ceratopsians.” Ankylosaurs had 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 had been all heading to the river to drink on the identical time, he says. However it is usually attainable that completely different species of herbivorous dinosaurs herded collectively for longer intervals for defence. The truth is, the tracks of two predatory tyrannosaurids had been additionally discovered close by.
“In trendy African ecosystems, giraffes, zebras and wildebeest kind these multi-species herds, and a part of that’s to do with completely different species having completely different skills to detect predators,” says Pickles.
Nonetheless, with only a single attainable ankylosaur footprint discovered thus far, 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 enormous, herbivorous dinosaurs in the identical small space, but additionally pointing in the identical route, I’d say that’s tantalising proof they had 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 had been no less than 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.
The truth is, based mostly on the width of the tracks and the truth that solely hind footprints have been discovered, Romilio suggests they had been actually 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 identified to kind mixed-species teams,” says Romilio. “It’s fully believable that some dinosaurs might have carried out the identical.”
Pickles dismisses Romilio’s suggestion in regards to the tracks. “They positively aren’t hadrosaur tracks,” he says.
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