When it comes to biting power, Tyrannosaurus rex was the undisputed king, a study has shown.
No living or extinct creature that ever walked the earth has been able to match the chomping force of the iconic dinosaur's jaws, researchers believe.
The findings, based on computer simulations, suggest that T. rex hunted large prey which it despatched with bone-crushing bites.
Experts have been divided on the jaw power of T. rex, which lived at the end of the dinosaurs' reign 65 million years ago.
Some believe it had a modest bite which limited the carnivore to scavenging dead carcasses. Others contend that T. rex was an active predator whose jaws were a fearsome weapon.
The research involved "reverse engineering" the jaw muscles of an adult T. rex using computer models.
No one knows precisely what the muscles of dinosaurs were like, so the scientists tested a range of values.
Even with a margin of error, the study showed that a T. rex bite was twice as powerful as previously predicted.
The force exerted ranged from 20,000 to 57,000 Newtons, or 4,496 to 12,814 pounds. This means T. rex's jaws were four times stronger than those of the American alligator, which has the most powerful bite of any living animal. One wild alligator measured by scientists bit with a force of 2,960 pounds.
To put the findings in context, the researchers scaled up the skulls of a human, alligator, juvenile T. rex and another meat-eating dinosaur, Allosaurus, to match the size of an adult T. rex.
In each case, bite forces increased as expected but they still failed to match that of an adult T. rex, suggesting that the dinosaur had the most powerful bite of any living or extinct land-dwelling animal.
Dr Karl Bates, from the University of Liverpool, who led the research published today in the Royal Society journal Biology Letters, said: "The power of the T. rex jaw has been a much debated topic over the years. Scientists only have the skeleton to work with as muscle does not survive with the fossil, so we often have to rely on statistical analysis or qualitative comparisons to living animals, which differ greatly in size and shape from the giant enigmatic dinosaurs like T. rex.
"As these methods are somewhat indirect, it can be difficult to get an objective insight into how dinosaurs might have functioned and what they may or may not have been capable of in life.
"Our results show that the T. rex had an extremely powerful bite, making it one of the most dangerous predators to have roamed our planet. Its unique musculoskeletal system will continue to fascinate scientists for years to come."