The giant ground sloth was nearly two metres high and weighed over a ton. The extinct dire wolf was as large as a modern jaguar but could not kill prey like the giant ground sloth on its own. But as a pack things were different. Dire wolves had learned to live together as co-operative families and the key to that was communication. Family groups originally banded together to help with rearing young and defending territory but the family also enabled them to hunt larger prey. For the first time in their history, the dogs could rival the cats as killers.