Were theropods hunters, scavengers or both?

Predatory dinosaurs could hunt living prey and feed on carcasses. Those behaviours are not mutually exclusive. Fossils preserve occasional meals, tooth marks and healed injuries, but they rarely reveal the full diet of an individual or how often it hunted rather than scavenged.

Evidence for an attack

The clearest evidence that a bite happened while an animal was alive is a wound that began to heal. A hadrosaur tail vertebra containing a tyrannosaur tooth fragment was surrounded by new bone. The prey survived long enough for healing, making the wound evidence of an attack on a living animal. It does not tell us whether the predator later caught the hadrosaur.

The famous “fighting dinosaurs” from Mongolia preserve a Velociraptor and Protoceratops in direct contact. Their claws and jaws are arranged as if the animals were engaged when rapidly buried. A dune collapse is a plausible explanation for the burial, but no observer recorded the final sequence, and the fossil cannot show which animal initiated the encounter.

What tooth marks can and cannot tell us

Tooth marks on bones, broken teeth, coprolites and gut contents help identify feeding. A bite on a carcass can look much like a bite inflicted during an attack, however. The location of marks, damage to living tissue and evidence of healing can narrow the possibilities, but many fossils cannot distinguish a kill from feeding after death.

Even a well-documented meal is a snapshot. It does not prove that every member of a species ate the same prey or used the same hunting strategy. Age, body size, health, season and access to food could all alter the choices available to an individual.

Were tyrannosaurs hunters or scavengers?

Tyrannosaurus rex was capable of both. Its powerful jaws and large teeth could process substantial prey, while its sensory and locomotor anatomy is consistent with active foraging. Healed bite evidence supports attacks on living animals. A large carnivore would also benefit from an accessible carcass rather than ignore it.

The old contrast between an obligatory scavenger and a predator that never scavenged is therefore a false choice. A fossil record that includes attacks on living prey does not reveal the proportion of meals obtained by each route. It supports flexible feeding, as in living large carnivores, without proving that every hunt succeeded.

Did theropods hunt in groups?

Trackways and bonebeds show that some dinosaurs moved or accumulated together. They do not by themselves demonstrate coordinated pack hunting. Several animals beside a carcass might have been drawn to food; a group of footprints could record travel rather than a chase. Rapid burial and the arrangement of bones also shape what survives.

Isotopic differences among juvenile and adult Deinonychus have been used to test whether family groups shared food. The results do not support a simple model in which adults provisioned young with the same prey. They do not prove that Deinonychus always lived alone: temporary gatherings and competition around food remain possible.

Not every theropod was a meat-eater

Theropoda includes lineages with varied diets. Some ornithomimosaurs, oviraptorosaurs and therizinosaurs had beaks, unusual teeth or other features consistent with feeding beyond persistent pursuit of large prey. Diet could differ even among close relatives. A theropod skeleton does not automatically imply a specialised hunter.

Claims about group behaviour and feeding are strongest when they join several lines of evidence: skeletal anatomy, bite marks, gut contents, coprolites, trackways and stable isotopes. Each has limits. The fossil record can establish that a particular interaction occurred or that an animal ate particular material, but it cannot turn every dramatic reconstruction into a witnessed scene. Profiles of Tyrannosaurus, Velociraptor and Deinonychus show how different evidence applies to individual theropods.