page_title: Tyrannosaurus
section_title: Feeding strategies
hierarchical_section_title: Tyrannosaurus / Paleobiology / Feeding strategies
caption_attribution_description: Tooth marks made by Tyrannosaurus rex. A, hadrosaurid metatarsal (UCMP uncatalogued) and closeup of tooth marks on distal articular surface. B, fragment of hadrosaurid pubis (CM 105) showing tooth marks on prepubic process. C, ceratopsid? frill element (TMP 1998.102.2) showing tooth mark. D, Triceratops right squamosal (YPM 53263) showing tooth marks on edge.
context_page_description: Tyrannosaurus is a genus of coelurosaurian theropod dinosaurs. The species Tyrannosaurus rex, often called T. rex or colloquially T-Rex, is one of the most well-represented of the large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous period, 68 to 66 million years ago. It was the last known member of the tyrannosaurids, and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.
  Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to its large and powerful hind limbs, Tyrannosaurus forelimbs were short but unusually powerful for their size and had two clawed digits. The most complete specimen measures up to 12.3 meters in length though T. rex could grow to lengths of over 12.3 m, up to 3.66 m tall at the hips, and according to most modern estimates 8.4 metric tons to 14 metric tons in weight.
context_section_description: Most paleontologists accept that Tyrannosaurus was both an active predator and a scavenger like most large carnivores. By far the largest carnivore in its environment, T. rex was most likely an apex predator, preying upon hadrosaurs, armored herbivores like ceratopsians and ankylosaurs, and possibly sauropods. A study in 2012 by Karl Bates and Peter Falkingham found that Tyrannosaurus had the most powerful bite of any terrestrial animal that has ever lived, finding an adult Tyrannosaurus could have exerted 35,000 to 57,000 N (7,868 to 12,814 lbf) of force in the back teeth. Even higher estimates were made by Mason B. Meers in 2003. This allowed it to crush bones during repetitive biting and fully consume the carcasses of large dinosaurs. Stephan Lautenschlager and colleagues calculated that Tyrannosaurus was capable of a maximum jaw gape of around 80 degrees, a necessary adaptation for a wide range of jaw angles to power the creature's strong bite.
  A debate exists, however, about whether Tyrannosaurus was primarily a predator or a pure scavenger; the debate was assessed in a 1917 study by Lambe which argued Tyrannosaurus was a pure scavenger because the Gorgosaurus teeth showed hardly any wear. This argument may not be valid because theropods replaced their teeth quite rapidly. Ever since the first discovery of Tyrannosaurus most scientists have speculated that it was a predator; like modern large predators it would readily scavenge or steal another predator's kill if it had the opportunity.
  Paleontologist Jack Horner has been a major proponent of the view that Tyrannosaurus was not a predator at all but instead was exclusively a scavenger. He has put forward arguments in the popular literature to support the pure scavenger hypothesis:
  Tyrannosaur arms are short when compared to other known predators. Horner argues that the arms were too short to make the necessary gripping force to hold on to prey.
  Tyrannosaurs had large olfactory bulbs and olfactory nerves (relative to their brain size). These suggest a highly developed sense of smell which could sniff out carcasses over great distances, as modern vultures do. Research on the olfactory bulbs of dinosaurs has shown that Tyrannosaurus had the most highly developed sense of smell of 21 sampled dinosaurs.
  Tyrannosaur teeth could crush bone, and therefore could extract as much food (bone marrow) as possible from carcass remnants, usually the least nutritious parts. Karen Chin and colleagues have found bone fragments in coprolites (fossilized feces) that they attribute to tyrannosaurs, but point out that a tyrannosaur's teeth were not well adapted to systematically chewing bone like hyenas do to extract marrow.
  Since at least some of Tyrannosaurus's potential prey could move quickly, evidence that it walked instead of ran could indicate that it was a scavenger. On the other hand, recent analyses suggest that Tyrannosaurus, while slower than large modern terrestrial predators, may well have been fast enough to prey on large hadrosaurs and ceratopsians.
  Other evidence suggests hunting behavior in Tyrannosaurus. The eye sockets of tyrannosaurs are positioned so that the eyes would point forward, giving them binocular vision slightly better than that of modern hawks. It is not obvious why natural selection would have favored this long-term trend if tyrannosaurs had been pure scavengers, which would not have needed the advanced depth perception that stereoscopic vision provides. In modern animals, binocular vision is found mainly in predators.
  A skeleton of the hadrosaurid Edmontosaurus annectens has been described from Montana with healed tyrannosaur-inflicted damage on its tail vertebrae. The fact that the damage seems to have healed suggests that the Edmontosaurus survived a tyrannosaur's attack on a living target, i.e. the tyrannosaur had attempted active predation. Despite the consensus that the tail bites were caused by Tyrannosaurus, there has been some evidence to show that they might have been created by other factors. For example, a 2014 study suggested that the tail in
caption: Tyrannosaurus tooth marks on bones of various herbivorous dinosaurs
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