The Biggest Rodent You’ll Never Meet

Imagine you crossed a capybara with a… I dunno, a hippo? You might get a good approximation for the largest rodent we have on record, the awkwardly named Josephoartigasia monesi.

This enormous creature lived around 3 million years ago, and is known only from a single fossilized skull. Well, a section of skull, as the lower jaw was missing. But that massive, nearly-two-foot-long skull has still yielded a lot of information about this gigantic rodent, who possibly weighed in close to 1 ton.

Some estimations were made about the missing lower jaw, at which point simulations of the creature’s bite could be made. And what a bite it turned out to be! While the muscles powering the jaw likely didn’t provide this much power, the bones’ bite capacity was 300 pounds at the front of the mouth, and 936 pounds at the back (close to crocodiles!)

With no coprolites to expose the animal’s diet, the next best place to look was the molars and impressive incisors (which, of course, would have been perpetually growing, as per all rodents.) Small nicks and chips can often reveal clues, and sometimes chemical traces, of an animals diet. But in this case, the potential strength of the teeth again overshadowed the other information gathered.

Josephoartigasia’s incisors were found to be strong enough to withstand forces greater than the jaw was even capable for making. But if his teeth were stronger than his bite (what?), were they needed for some purpose other than eating?

One possible explanation is that their size and strength was actually there to allow Josephoartigasia to dig and scrape through roots. They weren’t just teeth— they may have been shovels, picks and shears too.

Source: Giant Fossil Rodent Had an Awesome Bite by Brian Switek, Laelaps