New York City rats are beasts of legendary size and ferocity. That reputation probably has more to do with East Coast attitude more than anything else. Even the largest of the city’s rats look puny in comparison to South America’s capybara – at sizes over 130 pounds, the largest rodent in the world. But even the capybara is a lightweight next to the largest rodent of all time. At an estimated weight of over a ton, Josephoartigasia monesi was truly a rodent of unusual size.

First described by paleontologists Andrés Rinderknecht and R. Ernesto Blanco in 2008, Josephoartigasia is only known from a 1.7-foot-long skull found in the 4-2 million year old rock of