World’s (new) largest rodent

For many years, the record holder for largest rodent of all time was the giant beaver Castoroides ohioensis, like the specimen shown above on exhibit in the Science Museum of MinnesotaCastoroides was common in North America (including Virginia) during the Ice Age. At an estimated mass of up to 200 kg (440 lbs), it dwarfed the largest living rodent, the 130-pound capybara (Hydrochoerus hydrochaeris) from South America (below, from the National Zoo).

In 2003 Marcelo R. Sánchez-Villagra, Orangel Aguilera, and Inés Horovitz reported new material from the rodent Phoberomys pattersoni from the Miocene of Venezuela that indicated its mass at around 700 kg (about 1500 lbs), easily surpassing Castoroides for the title of world’s largest rodent (see their abstract here).

This week Andrés Rinderknecht from the Museo Nacional de Historia Natural y Antropología and R. Ernesto Blanco from the Instituto de Física described a new rodent from Uruguay in the Proceedings of the Royal Society B. Josephoartigasia monesi is based on a nearly complete skull, which in itself is unusual (most fossil rodent remains are isolated teeth.)

Josephoartigasia monesi is a huge rodent, with a skull more than twice the length of a capybara’s. Rinderknecht and Blanco calculate that J. monesi had a mass of around 1400 kg (over 3000 lbs), twice the size of Phoberomys pattersoni.

Rinderknecht and Blanco’s complete paper is available here (pdf format).

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5 Responses to World’s (new) largest rodent

  1. Doug Shore says:

    That’s quite a rodent. Why are all the new giants coming from South America?

  2. Alton Dooley says:

    Probably because no one’s really looked there much in the past. I’d expect to see a lot of new discoveries of large animals in South America, Africa, and Asia in the coming years just because North America and Europe are so well explored.

    Not that we’re giving up! I think we still have the largest coelurosaurian (Tyrannosaurus), the largest ceratopsian dinosaur (Triceratops), the largest pterosaur (Quetzalcoatlus), and possibly the largest flying birds (the Pelagornithidae). And various new dinosaur bonebeds out west, and sites like Carmel Church, show that even here there are still large fossils awaiting discovery.

  3. Doug Shore says:

    I hear that. I often read how the Cedar Mountain formation is one of the last untaped dinosaur beds in North america, but a couple new cases pop up now and then ie. Gray Fossil site. And old overworked beds still seem to yield surprises ie. Hell Creek.

    Actually, South America hold the record for biggest flying bird (Argentavis), but Airlornis comes close. And all the fossil focus in Africa seems to be centered on our early years. But apparently there is enough that the museum nearest to me is doing an exhibit about African dinosaurs this summer (i can’t wait). And Asia is churning out, like, half the new dinosaurs discovered each year.

  4. Alton Dooley says:

    We had a small exhibit on Chinese dinosaurs at VMNH last year, and one on African dinosaurs around 4 years ago. China, in particular, will continue to produce a bunch of new discoveries–it’s a huge country, with a well-funded IVPP and Geological Museum, each with large numbers of well-educated, highly capable paleontologists.

    Africa has similar potential (from the unexplored geology standpoint), but political instability slows things down there (early Eocene whales have the same problem–the best localities are in Pakistan and Afghanistan).

  5. Doug says:

    Oh, politics. Politics ruins everything. When i read Dragon Hunter, it talked of how Roy Chapmen Andrews had to deal with China’s political system, how he had to bribe officials and deal with anti-american propaganda ( I think he had better luck with the bandits he met in Mongolia).

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