Josephoartigasia Monesi lived about three million years ago in South America, and is known from a single, enormous, half-metre-long skull. Its head alone was the size of an entire beaver — itself considered a rodent of unusual size.
"It's quite a fearsome looking thing," acknowledged Philip Cox, an anatomist at the University of York, in an interview with CBC's As It Happens.
Cox used CT scanning to create a computer model of the skull.
Like other rodents, Josephoartigasia had enormous front teeth.
Using engineering techniques, Cox predicted that the giant ancient rodent would have had the bite strength of a tiger. But its teeth could actually withstand three times the force applied by biting.
Cox suggested the teeth were likely used for other activities besides just eating. They may have been used for digging – something that naked mole rats used their teeth for — or for fighting. The giant rodent may have bared its tusk-like teeth to defend itself from predators.
Or it may have had fights with others of its species that involved running, open-mouthed, at each other – "maybe in the same way that male elephants clash their tusks together," Cox said.
The findings were published in the Journal of Anatomy.