July 26, 2014
New Evidence Suggests That Tyrannosaurs Traveled Together In Packs
redOrbit Staff & Wire Reports - Your Universe Online
Three sets of tyrannosaur tracks discovered in northeastern British Columbia reveal the bipedal carnivores likely traveled in packs, according to new research published in Wednesday’s edition of the journal PLOS ONE.
According to Emily Chung of CBC News, this marks the first time that more than a single tyrannosaur print has ever been found in one place. That alone made the find interesting enough, since it allows paleontologists to determine how the creatures walked, but more exciting is the fact that some of the prints were made by dinosaurs with different-sized feet.
The tracks were originally discovered by Aaron Fredlund, a hunting guide from Tumbler Ridge, BC, in the fall of 2011. Chung explained that Fredlund was guiding a group of moose hunters when he found the tracks while looking for a place to cross a river. While he had never seen dinosaur prints before, he was a tracking expert and was able to detect a massive print made by a three-toed foot that was more than 60 centimeters long.
Lead author Richard McCrea said that he believed Fredlund’s discovery was a lucky one, as most people either would not have noticed them or would have dismissed the possibility that they were actually dinosaur tracks. When he was first contacted by the hunting guide, McCrea was studying in Australia, but rushed to the site upon his return to Canada in the hopes that he and his team could make casts of them before the first snowfall of the year.
They returned the following year and were able to find additional tracks, which they attributed to three different types of tyrannosaurs with feet that had slightly different sizes, Chung said. Based on the size of the feet, the dinosaurs would have been about 2.5 meters tall at the hip and 10-12 meters long from head to tail. The size of those prints means that they likely belonged to one of three tyrannosaurs - Albertosaurus, Gorgosaurus and Daspletosaurus.
The footprints are all pointed in the same direction (towards the southeast) and are only within 8.5 meters of one another, noted Amina Khan of the Los Angeles Times. Based on the fact that large predators tended to be rare in the region at the time, the authors said that it seems extremely unlikely that three tyrannosaurs just happened to be in the same place, at the same time, walking in the same general direction.
“Tyrannosaurs were a rare part of the fauna, there is no sign of an obstacle that would create a bottleneck requiring tyrannosaurs to walk the same path, and the detail of the tracks – down to foot scales on some – hint that they were all made around the same time, while substrate conditions were consistent,” said Brian Switek of National Geographic. “That two, if not three, tyrannosaurs were walking together is the simplest explanation of the pattern.”
“So did tyrannosaurs hunt in packs? Maybe. The tracks, stunning as they are, can only take us so far,” he added. “There remains a shred of doubt that these footprints were made by a single social group. If the tracks showed some sign of interaction between the animals – like raptor footprints that show one adjusting its course to move out of the way of another – then we could be sure.”