Harry Pettit, Senior Digital Technology and Science Reporter - The Sun




A GIANT rat weighing up to 80 kilos scurried through the Brazilian rainforest 10million years ago.

Scientists say the oversized rodent had giant teeth and stood as tall as a human when propped up on its hind legs.

Named Neoepiblema acreensis, it's one of the biggest rodents ever to roam South America.

The skulls of two creatures were found at a fossil site at Acre in the western Brazilian Amazon.

One was almost complete and the other included a fragment of crania, the part that encloses the brain.

It was so well preserved it even had impressions of parts of the brain that processed smell and thoughts, according to a study on the finds.


A giant rodent roamed the Brazilian rainforest 10million years ago

Lead author Dr Jose Ferreira said: "Neoepiblema was about five feet long and weighed around 80 kg.

"It surpassed the capybara, the largest living rodent which is about 60 kg."

To put this in perspective, the average brown rat today has a body length of less than a foot and weighs about 200 grams.

The rodent is an extinct relative of the chinchillas and inhabited the western Brazilian Amazonia in prehistoric times.

It lived in swampy environments that existed there before the emergence of one of the largest tropical forests in the world.

Its size meant it had few predators, perhaps just large crocodiles that would have used "sit and wait strategies", pouncing if one wandered past.

Neoepiblema, described in the journal Biology Letters, was not very bright.

A digital reconstruction of its brain using CT scans showed it was very small, weighing just over 100 grams. A human brain is about 1.3 kg.



Dr Ferreira, of the Federal University of Santa Maria, explained: "Although Neoepiblema was one of the largest rodents ever, the brain of this giant rodent was very small relative to its body mass."

The creature's brain was small because thinking power burned up lots of energy – which the rate needed to power its huge body.

There are more than 2,000 living species of rodents, constituting almost half the types of mammals on Earth.

They include such diverse groups as porcupines, beavers, squirrels, marmots, pocket gopher and chinchillas.


The largest living rodent is the capybara, which weighs up to 60 kg

Dr Ferreira said: "Some extinct South American members of this clade reached giant body size during the Late Miocene, some 10 million years ago.

"Neoepiblema acreensis is one of the largest rodents that inhabited South America."

Josephoartigasia monesi, a rodent closely related to guinea pigs, which lived in South America three million years ago, is the largest fossil rodent ever found.

With an estimated body mass of 2,200lbs (1,000 kilos), it was similar in size to a buffalo.