Bite Force Measured for Largest Ever Rodent
Today the largest living rodent is the Capybara of tropical South America, which weighs in at an impressive 60kg. However, 4 million years ago South America was dominated by a group of even more enormous rodents, the largest of which was Josephoartigasia monsei. New research from the University of York has revealed that this huge rodent had a far more powerful bite then previously suspected, sparking debate about how it may have used them.
Josephoartigasia is the largest rodent ever discovered. At 1.5 metres tall and weighing around 1000 kilograms it was certainly an impressive animal. Its incisors alone reached 30cm in length and it is these which researchers have been investigating. In order to examine the fossil in more detail researchers CT scanned the skull and then used a computer programme to explore the pattern of stress on the bones. This kind of analysis gives a good indication of how the animal could have moved and used its skull in life and can even be used to estimate bite force. In this case the results showed that Josephoartigasia would have been capable of generating a bite force of 1400 newtons. For context this is greater then some modern predators, lions for example only generate around 690 newtons. Significantly however, the reconstruction also showed that the incisors could withstand a force three times as great as this suggesting that they were used for something other than simply biting.
At the time Josephoartigasia lived it would have shared its estuarine environment with a range of other, smaller rodents, as well as some of prehistoric South America’s more iconic residents. In fact the dangers of predation by sabre-tooth cats, or the carnivorous ‘terror birds’ may have been one reason for its prodigious size. It may also suggest a defensive use for such powerful teeth. The researchers drew the comparison to elephant tusks, which have multiple uses aside from feeding, such as display or digging for roots and tubers. It seems likely that Josephoartigasia would have used its enormous incisors in a similar fashion.
Josephoartigasia died out around 2 million years ago. Exactly why these previously successful animals died out isn’t clear, but at the end-Pliocene to early Pleistocene when they lived the climate was cooling and becoming drier. This may have caused the wetlands upon which Josephoartigasia relied to shrink, their ranges contracting until eventually they could no longer sustain these enormous rodents and their relatives.
Featured Image: Wikimedia Commons