The Mapusaurus probably worked together as a pack in order to kill animals larger than themselves, such as the 125-foot, 100-ton Argentinosaur. The Argentinosaur was a plant-eating dinosaur, and may have been the largest land animal that ever lived.

Mapusaurus would likely run in, slice out gouges of an animal, and then retreat, waiting for it to bleed to death. Working together would make this a different hunting technique than that of dinosaurs such as the Tyrannosaurus rex.

Mapusaurus were probably slightly bigger than T. rex. Although both animals were large, bulky “macropredators” that walked on their hind legs and used their teeth as their basic weapons, there were significant differences.

“Mapusaurs have long, thin skulls with knife-like teeth and jaws that can close very fast,” Philip Currie said. “T. rex has a short skull with powerful, banana-shaped teeth better for biting through bone.”

The Mapusaurs’ teeth were about the length of one human hand and had thin, blade-like teeth capable of slicing the flesh of other dinosaurs, unlike T-rex’s stronger, spike-shaped teeth that crunched through its prey. Because Mapusaurus had smaller brains, and heavier, shorter legs than T-rex, it would not have been able to run as fast on its hind legs. However, since it chased slower, larger animals, it was able to hunt efficiently.

“During the attack, what it could do is run in, take a big gouge out of an animal, move back and then hopefully wait for it to bleed to death. A very different kind of technique.”