 Evidence that Daspletosaurus lived in social groups comes from a bonebed found in the Two Medicine Formation of Montana . The bonebed includes the remains of three Daspletosaurus , including a large adult , a small juvenile , and another individual of intermediate size . At least five hadrosaurs are preserved at the same location . Geologic evidence indicates that the remains were not brought together by river currents but that all of the animals were buried simultaneously at the same location . The hadrosaur remains are scattered and bear many marks from tyrannosaur teeth , indicating that the Daspletosaurus were feeding on the hadrosaurs at the time of death . The cause of death is unknown . Currie speculates that the daspletosaurs formed a pack , although this cannot be stated with certainty . Other scientists are skeptical of the evidence for social groups in Daspletosaurus and other large theropods ; Brian Roach and Daniel Brinkman have suggested that Daspletosaurus social interaction would have more closely resembled the modern Komodo dragon , where non @-@ cooperative individuals mob carcasses , frequently attacking and even cannibalizing each other in the process . 
