…and this is a 
Monster mouse
Category: Fossils • Organisms • Science
Posted on: January 18, 2008 1:19 AM, by PZ Myers
The capybara is the current champion for rodents of unusual size — it weighs about 60kg (about 130 pounds); another large rodent is the pakarana, which weighs about a quarter of that. Either one is far too much rattiness for most people to want hanging around.
Now there's another king of the rodents: Josephoartigasia monesi, which is estimated to have tipped the scales at about 1000kg, over a ton. Don't worry about getting bigger rat traps; these beasties have been extinct for perhaps 2 million years. I've put a few pictures from the paper describing this new species below the fold.
This is the skull of the type specimen.
Skull of J. monesi sp. nov. (holotype, Museo Nacional de Historia Natural y Antropologıa MNHN 921) in (a) dorsal, (b) frontal, (c) ventral and (d ) lateral views.
To help get an idea of the size of this skull, here's a pakarana skull (left), capybara (middle), and J. monesi (right). It's huge!
And what did this rodent the size of a cow look like while alive? Here's a reconstruction, drawn to scale with a pakarana.
There is no suggestion that it lived in a fire swamp — its habitat was probably forested river deltas.
Rinderknecht A, Blanco RE (2008) The largest fossil rodent. Proc. R. Soc. B doi:10.1098/rspb.2007.1645.
Life Science
Comments
Well no wonder Moses disobeyed God by not bringing two of these aboard the ark.
Posted by: Brownian, OM | January 18, 2008 2:12 AM
Egads! That's a lot of rodent.
Posted by: Knight of L-sama | January 18, 2008 2:45 AM
My cat would still try to eat one in spite of the size difference.
Posted by: Stanton | January 18, 2008 3:05 AM
too much rattiness?! *impossible*.
http://www.danamania.com/tmp/moremore.jpg
I must admit, I wish there were more large rodents still around, if just to give cats a bit of a scare from time to time.
Dana
Posted by: Dana Sibera | January 18, 2008 3:08 AM
How can capybara be too much rattiness? I think they're rather cute.
Bob
Posted by: Bob O'H | January 18, 2008 3:21 AM
We've usually had rats, although my youngest decided to get a guinea pig after her last rat died of old age. Even so, I've to a stupid Akita that would eat just about anything, he takes down anything that gets into his yard including possums, cats, birds, you name it, he'll "play with it" to death. In the last week, he's been desperately trying to get a hold of a big old raccoon that's so far been smart enough to stay up on the fence where he can't be reached.
Posted by: Cephus | January 18, 2008 4:22 AM
I second #3 ....
We used to have a quarter-Siamese tabby, called "Hermann" (as in Goering) who only blinked once, if I remember correctly, when faced with an adult goose - it was declared an offical draw.
He certainly did NOT care what size a DOG was - they were all clockwork toys for his amusement.
Giant RODENT? Let me at it!
Posted by: G. Tingey | January 18, 2008 4:27 AM
Ha! I knew The Princess Bride was a true story! I knew it!
R.O.U.S. Rodents of unusual size. Proof!
OEJ
Posted by: One Eyed Jack | January 18, 2008 4:53 AM
Mike Huckabee says, "Them's good eatin!"
Posted by: Ralph Kramden | January 18, 2008 5:12 AM
OMG! Think of the wheel you'd need for your cage... And just forget the plastic run-around ball...
Posted by: Moses | January 18, 2008 6:21 AM
Did it live on an island?
Posted by: Lago | January 18, 2008 6:42 AM
No, it lived in Uruguay. Megafauna were a lot more common in the Pliocene.
Posted by: Argus | January 18, 2008 6:50 AM
Posted by: Fernando Magyar | January 18, 2008 6:52 AM
I am struck by the fact that the largest rodent ever known is named after the founder of Uruguay.
Posted by: Fragano Ledgister | January 18, 2008 7:02 AM
Bob O'H asks, "How can capybara be too much rattiness? I think they're rather cute."
And-- no joke-- they're good eating, too! Venezuelans serve the meat dried and salted. Delicious. Like pork cracklins without the grease.
Too bad about J. monesi going extinct. A rodent that size could end world hunger. :-)
Posted by: hoary puccoon | January 18, 2008 7:20 AM
Josephoartigasia monesi? Gosh, one has the previlege to get to name a major new mammal species (however extinct) and yet can't come up with a better name than this piece of fake Latin?
Naming a giant rodent after José Artigas is doing neither any good! I'd call it Megamus delticola or Macrocastor giganteus -- and even if one's stuck with Josephoartigasia, I'd at least go for something meaningful, like J. lacustris.
(Or forget Latin altoghether and just use some Guarany binom, like Kukulele apajere or something.)
Posted by: António Martins-Tuválkin | January 18, 2008 7:32 AM
Of course they went extinct. They didn't have tentacles.
http://www.boingboing.net/2008/01/17/tentacle-arms-for-sq.html
Posted by: Lassi Hippeläinen | January 18, 2008 7:32 AM
Oh but it is so CUTE!
How can it be too much rattiness for anyone?
I am struck by a story told to me by a vet friend of mine...
A woman comes into the practise holding a wee cardboard box with airlholes. Inside inside, under a miniature patchwork blanket and ontop of a pink satin pillow is a baby rat.
"What is it?" The woman asks? "It is so cute."
"That is a baby rat" My friend's colleague told the woman.
She shrieks and throws the box, rat and all, across the surgery screaming, "Kill it!".
I don't understand some people's aversion to the cute Rattus.
Posted by: maxi | January 18, 2008 7:34 AM
As I said on Dr. Wilkin's blog. That's not megafauna. The Diprotodon is real megafauna....
Posted by: Brian English | January 18, 2008 7:46 AM
Let's not forget the noble New York sewer rat. Folk could ride those bloody things to work if they wanted.
Posted by: RMPink | January 18, 2008 8:05 AM
It's an in-joke. In the late 19th century Florentino Ameghino named lots and lots of fossil mammals from Argentina by taking the first and last names of famous paleontologists, squeezing them into more-Spanish-than-Latin, and adding -ia or -a.
Posted by: David Marjanović, OM | January 18, 2008 8:22 AM
"Oh, Speak! I'm sorry, I didn't mean it. Of course, you're not a dog, you're a wonderful, lovely rodent. And there's nothing wrong with that. No! And if that's your lifestyle choice, then we'll stand behind you all the way."
Posted by: Jim A. | January 18, 2008 8:34 AM
Capybaras are ridiculously cute. Don't know why they get such a bad name. My wife and I enjoyed watching them splash in to the water when we were in the Pantanal.
Posted by: Casey S | January 18, 2008 8:49 AM
Two million years old. I suspect that we will eventually find remains that are twelve thousand years old, with a curiously empty record after that. Just a hunch.
Posted by: John Vreeland | January 18, 2008 9:10 AM
Early hominid to wife: "Hmmm, looks like we're going to need a bigger cat"
Early Behe to colleagues: "Dayum! Will you look at the irreduceable complexity on that ! Gonna need a bigger trap!"
Posted by: Ian H Spedding FCD | January 18, 2008 9:11 AM
Does the Catholic Church classify josephoartigasia monesi a fish?
Posted by: Doug | January 18, 2008 9:17 AM
Rats are awesome pets. Hearty too! My daughter has had one of her rats for going on 18 months now. It got a tumor on the side of it's head, which grew to the size of a blueberry in about 36 hours, squished her eyeball, and then just disappeared. Other than being blind she seems perfectly happy.
Posted by: mn_monkey | January 18, 2008 9:20 AM
Imagine using J. monesi for "knock-in" or knock-out" gene testing in the lab.
Posted by: Rick Schauer | January 18, 2008 9:42 AM
Extinct for 2 million years, you say?
I could have sworn I saw one of those near a trash pile here in Naples, just the other day! Or maybe the other rats around here are just evolving into megafauna.
Posted by: Katrina | January 18, 2008 9:51 AM
David beat me to a comment about Ameghino's names for fossils, but for people's amusement, it may be worth mentioning a few that stand out:
Guileilmofloweria (William Flower)
Ricardolydekkeria (Richard Lydekker)
Amilnedwardsia (Arthur Milne-Edwards)
Maxschlosseria (Max Schlosser)
Thomashuxleya (Thomas Huxley)
Posnanskytherium (Posnansky's beast)
Henricofilholia (Henry Filhol)
Posted by: N. Wells | January 18, 2008 9:57 AM
Hate me if You want, but 1000 kg are one ton exactly.
And capibaras are cute.
Posted by: F.Caccin | January 18, 2008 10:10 AM
I didn't dare add examples because I don't know by heart which ones are really by him and which are just continuations of the tradition. One such case where I'm not sure is Henricosbornia after Henry Fairfield Osborn.
It goes without saying that Ameghino posthumously got Florentinoameghinia.
Posted by: David Marjanović, OM | January 18, 2008 10:14 AM
They are one tonne (metric ton) exactly. A British ("long") ton is less, and an American ("short") ton is less still. That's because they consist of a certain number of hundredweights, and while an American hundredweight has 100 pounds, a British one has 120, which must be why it's called hundredweight...
Posted by: David Marjanović, OM | January 18, 2008 10:18 AM
Too much rattiness? Nah. To me it looks like a giant guinea pig. Was it a herbivore like the capybara? I bet it was.
Posted by: Robert Madewell | January 18, 2008 10:29 AM
David, probably the same sort of thinking that gave us 16 ounces (from the Latinuncia meaning one twelfth) in a pound and 5280 ft in a mile (from the Latin mille meaning 1000)
Posted by: Jim A | January 18, 2008 10:45 AM
By default, yes, the Catholic church would call this beast a fish. This rodent predates Ratzi and has no rattziness. Also, they were on the ark but gnawed through the hull. How do you think that mountain in Turkey got its name-- ARRR, A RAT!
On a distantly related note Ratzi canceled an appearance at Rome University (good) but got favorable press with his pot-calling-the-kettle-black explanation (bad).
Posted by: mothra | January 18, 2008 10:51 AM
Josephoartigasia actually belonged to the Dinomyidae, a formerly diverse group of South American rodents, with the pakarana as the only living representative. So it probably looked somewhat like a guinea pig, it was much closer to them than to real mice or rats, and yes, the paper says it was herbivorous.
Henricosbornia is really by Ameghino (so are about a gigantillion of synonyms for that one, originally classified in two or three different orders), and I'm quite sure so are those listed in comment #30, except Posnanskytherium, which I had to google (it was named in 1943 by Liendo Lazarte). Another thing Ameghino often did was anagrams. Thus we have Toxodon and Xotodon, Macrauchenia and Cramauchenia, Astrapotherium and Traspoatherium...
Posted by: Lars Dietz | January 18, 2008 10:53 AM
Father! FATHER!!!
It's that giant mouse again!
Posted by: Rav Winston | January 18, 2008 10:54 AM
You beat me to it. It's been 10 years, and I still think back to that delicious rodent.
Posted by: Davis | January 18, 2008 11:06 AM
"Biggest rodent"? If it was that big I would be able to see it from here!
Posted by: Bob L | January 18, 2008 11:12 AM
Biggest rodent my left mandible!
It is too, much too apparent you have never seen my cat!
Posted by: Mooser | January 18, 2008 11:17 AM
Thufferin' thuckatash, that'th a big mouthe.
Posted by: Scrofulum | January 18, 2008 11:33 AM
You're gonna need a bigger
boatmousetrap.Posted by: Brownian, OM | January 18, 2008 11:46 AM
How can it be 2 million years since it died out? We all know the earth is only around 6,000 years old. ;)
Posted by: Randy | January 18, 2008 12:30 PM
Re #33:
I stand corrected.
Didn't know things could get that non-metric.
Posted by: F.Caccin | January 18, 2008 12:48 PM
Giant space hamsters are real!
Posted by: coathangrrr | January 18, 2008 1:04 PM
"Oh, Speak! I'm sorry, I didn't mean it. Of course, you're not a dog, you're a wonderful, lovely rodent. And there's nothing wrong with that. No! And if that's your lifestyle choice, then we'll stand behind you all the way."
You're playing with fire Mr. Excitement.
It wouldn't freak the cats out too much to have this thing around... since if it was around then the American Lions and Cheetahs would be too. And saber-tooth cats as well. And those 70 MPH pack-hunting giant wolves!
I'd like more megafauna.
Posted by: Sarcastro | January 18, 2008 1:19 PM
Mmmm labba. Must go back.
#33 David the British one has 112 pounds. THAT'S why it's called a hundredweight. 14 X 8 see. Bleedin obvious innit. 120 pounds, well there's no sense in that is there?.
Posted by: Gav | January 18, 2008 1:35 PM
Of course.
It's short for mille passuum "1000 strides" and not supposed to have any relation to feet.
Sorry for misremembering the number of pounds in a UK hundredweight. I don't have my dictionary here in the university. (And I've never actually encountered a hundredweight in the wild, IIRC.)
Posted by: David Marjanović, OM | January 18, 2008 1:59 PM
Of course but since stride isn't a unit... it was more important to define it as an integer multiple number of rods... making it a significantly longer distance than the Roman mile. And of course your British hundredweight is an even number of stone... Don't confuse statute and international miles. And you Brits can keep your new-fangled, steam-powerd Imperial gallons, we'll stick with Queen Anne's wine gallon thank-you-very-much.
Posted by: Jim A | January 18, 2008 2:20 PM
"No, it lived in Uruguay. Megafauna were a lot more common in the Pliocene."
The region was estuarine and deltaic and near the shore, and was found along with large birds as well. These are common indications of possible island formations where birds and rodents increase greatly in size. What is Uruguay shore-line now, could very well have been islands then. In other words, an island cannot be ruled out simply by saying it was "Uruguay." And the idea that this region may have been broken off into a small grouping of islands, should be considered...
Posted by: Lago | January 18, 2008 2:35 PM
They would have been even more impressive if they'd lost their myostatin gene and gained a over-producing follistatin gene. At least that worked in mice.
BTW, mentioning myostatin is the perfect doping for any blog. If you want to further increase traffic use "myostatin blocker" or "myostatin pics".
Posted by: sparc | January 18, 2008 3:23 PM
I figure England is prepared for just such an eventuality:
http://en.wikipedia.org/wiki/Image:London_Eye_Twilight_April_2006.jpg
Posted by: Ichthyic | January 18, 2008 3:45 PM
Of course but since stride isn't a unit... it was more important to define it as an integer multiple number of rods... making it a significantly longer distance than the Roman mile.
A Roman stride actually was a unit: 5 Roman feet (~4.86 modern feet). A Roman mile was 5,000 Roman feet. The English just didn't remember since the Germanic tribes had misappropriated the word for several different measuring lengths.
Posted by: Sarcastro | January 18, 2008 5:16 PM
Holy Toledo! Too bad those things aren't still around to gnaw through mountains and provide tunnels for new highway and railroad construction.
Rats are cool. We had pet rats when I was young. We started with a pair, who got married and had babies. Fortuntely, all the babies were boys, so a population explosion was averted. Three of four years later, it was all over.
They sure were fun, though. We made mazes for them on the kitchen floor... And they'd eat anything! I loved throwing a handful of raw spaghetti in their tank and watch them go at it. They'd each hold a stick of spaghetti in their little hands and eat it end-to-end, all the while sounding like a half-dozen little typists hard at work. They loved any kind of pasta, peanuts, brazilnuts, filberts, broccoli, apples (core, seeds and all) but the thing they went berserk over was cooked chicken. They LOVED that. Omnivores rock.
OMG I am such a nerd. :-)
Posted by: Kseniya | January 18, 2008 5:26 PM
Eh, but phorusrhacids are not island indicators. Rather to the contrary, I suppose.
Posted by: David Marjanović, OM | January 18, 2008 6:51 PM
When I saw the words "monster mouse", what went through my mind was a computer pointing device the size of a volkswagen.
-jcr
Posted by: John C. Randolph | January 18, 2008 8:59 PM
"But Wesley, what about the R.O.U.S's?"
"Rodents of Unusual Size? I don't believe they exist...ARRGH!"
Posted by: lawyer/scientist | January 18, 2008 11:31 PM
Dave,,,
The birds are one line of evidence, The idea that they probably ate water plants is another line of evidence as well, and so is where the fossil was found and what type of matrix it was found in. The idea of a common trend of usually small animals becoming large on islands is also another line of evidence.
I am saying there are enough lines of evidence to consider the very real possibility of island formations in that region at the time as a driving force in selecting for such a large rodent.
For example, as far as I can tell with a quick google search, this is the general area where the fossil was found:
http://kitesurf.com.uy/phpBB2/userpix/2_DSCF0909_1.jpg
I believe that is, "Kiyu beach" where the paper says the fossil was found. I do not think the region possibly being an island at the time the rodent lived as being too far fetched, do you?
Posted by: Lago | January 19, 2008 1:05 AM
#49: "It's short for mille passuum "1000 strides" and not supposed to have any relation to feet."
The Romans obviously walked on their tentacles.
Posted by: Lassi Hippeläinen | January 19, 2008 5:18 AM
Water plants... but not marine ones, I suppose?
Also, keep in mind that this is not the first superhuge rodent from Mio-/Pliocene South America. Eumegamys, Telicomys, and Phoberomys come to mind.
Well, I'll try to download the paper on Monday.
Posted by: David Marjanović, OM | January 19, 2008 8:20 AM
Wait. "The size of a cow"? Then what is all the media buzz about? Eumegamys is supposed to be the size of a small rhino!
Posted by: David Marjanović, OM | January 19, 2008 8:22 AM
According to the paper, J. monesi is substantially larger than Phoberomys, previously claimed to be the largest rodent. No direct comparison is made to Eumegamys, though. Only the skull is known, but the body mass is allometrically estimated at 1211 kg, much more than the 400-700 kg for Phoberomys.
Posted by: Lars Dietz | January 19, 2008 10:27 AM
And that super_capybaras would fill the niche of water buffaloes? probably if living today they be named "buffalo-rats".....
Posted by: Edgar | January 19, 2008 11:09 AM
"Water plants... but not marine ones, I suppose?"
Well yeah, there is certainly the idea that this thing could have also been hippo-like analogue something like you'd see with early elephants at Fayum.
Posted by: Lago | January 19, 2008 11:33 AM
I was told, several times, in Venezuela that Chiguiri (Criollo for Capybara) are considered fish by Catholic folk. Ranchers would harvest them for sale during Lent. They could make enough off the chiguiri harvest to pay their year's ranching expenses. And, yes, they are quite tasty.
Was in a Chinese resturant a while back. Guy in front of me at the check out had a rat on his shoulder. Because pets are not allowed in resturants, I suppose it was a seeing-eye rat.
Posted by: Jim Thomerson | January 19, 2008 6:37 PM
I was told, several times, in Venezuela that Chiguiri (Criollo for Capybara) are considered fish by Catholic folk.
*sigh*
Posted by: Ichthyic | January 19, 2008 6:55 PM
"I was told, several times, in Venezuela that Chiguiri (Criollo for Capybara) are considered fish by Catholic folk.
*sigh*"
Well, cladistically speaking...
(Sorry)
Posted by: Lago | January 19, 2008 8:35 PM
I'm liking this particular reconstruction:
http://www.geocities.co.jp/NatureLand/5218/jyosefoa-tigasia.html
Posted by: Hai~Ren | January 20, 2008 4:28 AM
It was Noah, not Moses. Oh dear
Posted by: mylo | January 21, 2008 12:19 PM