Scientists have long debated whether the legendary Tyrannosaurus rex was a ferocious hunter or just a scavenger that feasted on the carcasses of already dead animals. In 2013, a broken tooth of a Tyrannosaurus rex found in another dinosaur’s tail bone offered the first hard evidence that the king of all carnivores hunted live prey.
Previous discoveries of dinosaur bones in the bellies of T-rex fossils, and even T-rex-shaped bites out of the tails of other dinosaurs, have suggested that the late Cretaceous era (66–100 million years ago) beast was a predator. But palaeontologists have not been able to rule out that T-rex was an opportunistic scavenger, and scientists say the latest research still cannot disprove that theory.
Researchers described in the Proceedings of the National Academy of Sciences, a US journal, the first discovery of a broken T-rex tooth in another dinosaur bone – in this case, in the vertebrae of a plant-eating hadrosaur.
“What we can tell from this ... is that a T-rex engaged a living hadrosaur,” said lead author Robert DePalma, of the Palm Beach Museum of Natural History in the US state of Florida. “What this present specimen does is it helps to essentially recrown the king.”
Poking out of two fused vertebrae is a major chunk of a T-rex tooth – a well-preserved crown spanning 3.75cm long. According to DePalma, T-rex teeth were as big as bananas, and they could regrow any lost during their lifetimes, much like sharks do today. The hadrosaur’s bone regrew over the injury, signifying that the creature escaped and healed, maybe even living for years afterwards. “The rarity of this piece is so extreme. We never in a million years expected to find something that was this clear in the fossil record,” added DePalma.
But researchers said their analysis does not mean the reputed dino bully ate only living beasts – it probably ate dead remains, too. “Like most modern large predators, it almost certainly did also scavenge carcasses,” said the study. Some experts have argued that the lumbering T-rex could not run fast enough to be a skilful predator.
Jack Horner, curator of palaeontology at the Museum of the Rockies in Bozeman, Montana, has described the T-rex as less like a lion and more like a hyena – a creature that fed on creatures large and small, both carrion and fresh-killed prey. Horner has also advanced the theory that T-rex’s short arms, big body and apparently strong sense of smell made it suited for sniffing out the dead.