T-Rex tooth embedded in TAIL of Hadrosaur proves that Tyrannosaur chased prey Scientists from the University of Kansas have discovered a T-Rex tooth embedded in the tail of a plant-eating Hadrosaur They claim their discovery proves the T-Rex was not a mere scavenger The fossil, found in Hell Creek, South Dakota, suggests that T-Rex chased the herbivore in a bid for a meal in a similar way to modern predators A tooth from a Tyrannosaurus Rex proves the creatures were active hunters that engaged in predatory behaviour instead of scavenging for carcasses, American scientists have said. The four centimetre-long tooth was left embedded in the tail of plant-eating Hadrosaur. Some 65 million years later, scientists discovered it stuck between two of the Hadrosaur's fossilised vertebrae. Scientists from the University of Kansas (pictured) have discovered a T-Rex tooth embedded in the tail of a plant-eating Hadrosaur, which they claim proves that the fearsome dinosaur was an active predator and not a scavenger Healed bone had grown around the tooth, fusing the vertebrae together, indicating the creature had a lucky escape. The Hadrosaur may have lived for months or even years after almost becoming a T-Rex meal. More importantly for dinosaur experts, the tooth provides strong evidence that the T-Rex was actively pursuing living prey. Opinion is still divided over the dining habits of the fearsome meat-eater, which sported pointed, bone-crunching teeth up to nine inches long. In films such as Jurassic Park, the T-Rex is portrayed as a terrifying, merciless hunter. But some scientists believe in reality it mainly fed on the carcasses of already dead animals and had more in common with hyenas than lions. However, the new discovery from a rock formation known as Hell Creek in South Dakota, US, does not conjure up a picture of a lazy scavenger. It suggests the Hadrosaur was fleeing for its life when the young T-Rex's jaws snapped on its tail. The four centimetre-long tooth (pointed out using a pencil) was left embedded in the tail of plant-eating Hadrosaur. Two fused fossilised vertebrae are pictured. The Hadrosuar's healed bone had grown around the tooth, indicating the creature had a lucky escape A US team led by Dr David Burnham, from the University of Kansas, wrote in the journal Proceedings of the National Academy of Sciences: 'The fused vertebrae and embedded tooth are the result of an attack on a live hadrosaur, not the scavenging of a carcass, and represent unequivocal evidence of a predator-prey relationship. We now have conclusive evidence that T-Rex indeed engaged in predatory behaviour. Whereas previously cited fossil evidence, such as isolated tooth marks, might have been easily misconstrued as the result of scavenging behaviour...our specimen includes the identities of the prey animal and the attacker, and the fact that the prey was alive when attacked. Moreover, the position of the injury - the tail - suggests that T-Rex could possibly have engaged in pursuit predation. The scientists pointed out that the position of the tooth was consistent with present-day pursuit attacks by predators. For example, African lions had been observed initially targeting the hindquarters of a prey animal in order to immobilise it. 'This Hadrosaur escaped and began to heal around the tooth lodged in its caudal vertebrae, providing evidence of the attack and the identity of the attacker,' the researchers added. The scientists believe that they have 'conclusive evidence' that T-Rex indeed engaged in predatory behaviour. Whereas fossils of tooth marks might have been misconstrued as the result of scavenging behaviour, the new fossil shows the identities of the prey animal and the attacker. An artist's impression of young T-Rex is pictured Such evidence is rare in the fossil record for good reason - prey rarely escapes. It was possible that many T.-Rex bite marks found on other fossils were not associated with bone healing because the prey had been killed, they said. The fact that the Hadrosaur got away did not necessarily mean T -Rex was a poor predator, the scientists argued. Between 45 per cent and 62 per cent of attacks by modern predators such as coyotes and lions end in failure or were aborted, but they are still viewed as efficient killers. The tooth is 3.75 centimetres long and 2.35 centimetres wide at the base and had been broken off at the root. It is identical in size and shape to teeth from T-Rex "sub-adults" housed in museums. Comparisons with teeth from two other predators strongly suggested the tooth was from T-Rex and not some other dinosaur.