Some 70 million years ago, three tyrannosaurs stalked together across a mud flat in Canada, possibly searching for prey.
The new insight comes from several parallel tyrannosaur tracks unearthed in Canada. The dinosaur tracks provide stronger evidence for a controversial theory: That the fearsome mega-predators hunted in packs.
The ferocious beasts may have "stuck together as a pack to increase their chances of bringing down prey and individually surviving," said study co-author Richard McCrea, a curator at the Peace Region Palaeontology Center in Canada. (See Images of the Giant Tyrannosaur Tracks)
Paleontologists have long debated whether Tyrannosaurus rex and its cousins, such as Albertosaurus, hunted alone or in groups.
While most researchers believe the predators were lone wolves, so to speak, multiple Albertosaurus specimens found in a single bone bed in Canada's Dry Island Buffalo Jump Provincial Park have led some to propose that tyrannosaurs were pack animals.
But finding groups of bones together isn't definitive evidence for pack hunting, because bones can move after death. Other circumstances can cause fossil skeletons to accumulate in one location. For instance, many carnivores wandered individually into classic predator traps, such as the La Brea tar pits in Los Angeles, but probably didn't hunt together in life, McCrea said.