Gigantic Fossilized Rodent Discovered
The fossilized skull of the largest rodent
ever recorded has been described by scientists for the first
time. The remains of the one-ton beast, found in Uruguay, indicate
that it would have been as big as a bull.
It is thought that the three-meter-long herbivore would have
roamed estuaries and forests 2-4 million years ago.
The mammal, which is more than 15 times heavier than the
largest living rodent, is described in the journal
Proceedings of the Royal Society B.
The authors say the animal would have lived alongside
carnivorous "terror birds" and sabre-toothed cats.
"If you are a rodent you cannot run so well so you would
have had to fight with these predators," said Dr Rudemar
Ernesto Blanco of the Institute of Physics in Montevideo,
Uruguay, one of the authors of the paper.
"It might have reached this size to protect itself."
The half-metre-long fossil
skull was discovered by an amateur palaeontologist in a
boulder on the Rio de La Plata coast in the south of the
remains had lain in the Museum of Natural History in
Montevideo for three years before being studied and
identified as a new species, Josephoartigasia monesi
It was recognised as a new creature by examining and
comparing its teeth with other known species of
"Its incisors are extraordinarily large - much
larger than any other rodent," said Dr Blanco.
The researchers have speculated that the creature
may have used the teeth to cut wood in a similar way
to a modern day beaver.
"The other possibility is that they used them for
The team spent nearly one year estimating the body
mass by comparing the skull with other living South
Most weigh less than 1kg. However, there are
exceptions such as the 60kg capybara ( Hydrochoerus
hydrochaeris ), and the closest living relative of the newly
discovered creature: the pakarana ( Dinomys branickii ).
The comparisons allowed them to estimate the creature's
weight at nearly one tonne (1,000kg) and predict its length.
"We think it was around three metres from the tip of the
nose to the tail," said Dr Blanco.
The creature's tail would have been little more than a
stump, according to the team.
The skull is not the first
oversized creature to be discovered in South America.
Other finds have included car-sized armadillos, giant ground
sloths and hook-beaked terror birds.
The previously largest-known rodent was Phoberomys
pattersoni , a 700kg creature nicknamed "guinea-zilla" and
discovered in Venezuela.
South America is well studied by biologists because its
plants and animals developed in isolation to the rest of the
world's flora and fauna.
Until the emergence of the isthmus of Panama, connecting it
to Central and North America about three million years ago,
the landmass had been cut off for tens of millions of years.
"It is highly probable that we can find more material of
this fossil and other related species," said Dr Blanco.