Just as modern meat-eating animals such as lions combine forces to pull down animals larger than themselves, many flesh-eating theropods hunted in packs. Roaming in gangs, heavily muscled, and armed with vicious claws and powerful jaws lined with sharp teeth, they were intelligent enough to band together before going into the attack. Like some sophisticated hunters today, dinosaurs may have developed tactics to outsmart their prey, such as luring them into traps or surrounding them before the attack.

Fossil evidence suggests that several kinds of carnivore dinosaurs hunted in packs. No modern reptiles hunt in packs like the dinosaurs did. Fossil remains from herbivores have been found to have several tooth marks on them, suggesting that these attacks were made by different sized predators, which may have hunted in packs.
Deinonychus are known to have hunted larger animals than their own size, some herbivores were up to 15 times the size of Deinocychus. But this was achievable only by hunting in numbers, this is supported by the evidence that fossil remains of multiple Deinonychus have been found near larger pray. This hunting behavior resembles modern carnivores such as the lion, when it hunts larger pray nowadays.

Carnivores possessed fairly larger brains, enabling them to hunt as a group.

Computer image showing a group attack on a larger Dinosaur.

Velociraptors are believed to be the smartest of predetors when hunting in a pack. Evidence shows that the raptors never went 'Straight for the Kill' but instead they slowly wounded the prey letting it eventually die of blood loss.