Giant prehistoric rat as large as a MAN who weighed 175 pounds and had a small brain lived in the Amazon rainforest 10 million years ago
- Neoepiblema acreensis weighed around 175 pounds (80 kg) and was five feet long
- But this huge rat had a small brain with a mass of just four ounces
- Skull fragments of two individual animals were found on an excavation in Brazil
Scientists have discovered a giant prehistoric rat the size of a human who lived in the Amazon rainforest ten million years ago.
It weighed around 175 pounds (80 kg) and reached five feet long – making it the largest rodent ever to roam South America.
To put this in perspective, the average brown rat nowadays has a body length of less than one foot and weighs around half a pound.
The beast called Neoepiblema acreensis, had two huge curved incisors and a very small brain that weighed only 114 grams.
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A giant prehistoric rat the size of a human who lived in the Amazon rainforest ten million years ago has been discovered by scientists (pictured, artist’s impression of the animal)
Called Neoepiblema acreensis, the beast had two huge curved incisors for gnawing nuts and prey, but had a small brain that weighed only four grams
The skulls of two individuals were found at a fossil location in Acre in Brazil.
One was almost complete and the other contained a fragment of the skull, the part that encloses the brain.
It was so well preserved that it even had impressions of olfactory bulbs – the area of the brain that processes odor – and the frontal and temporal lobes involved in thoughts and actions.
WHAT ARE MEGAFAUNA?
The word ‘megafauna’ is derived from the Latin words for ‘big’ and ‘animals’.
In the context of Australia and New Zealand, it refers to animals that died collectively about 46,000 years ago in a massive extinction.
Although many of them were marsupials – including giant kangaroos and wombats as well as other strange animals such as the marsupial lion – there were also huge snakes, lizards, and birds in ancient Australia.
These animals had existed here for about 11 million years, and within a few thousand years most of these giant animals disappeared.
Main author Dr. Jose Ferreira said: ‘Neoepiblema was about five feet tall and weighed around 80 kg, which exceeds the capybara, the largest living rodent that is around 60 kg.
“This rodent is an extinct relative of the chinchillas and pacaranas and lived in western Brazil about 10 million years ago.
“He lived in swampy environments that existed before the emergence of one of the largest tropical forests in the world.”
The size meant that it had few natural predators, but it is thought that large crocodiles would have sat and waited for one to walk by and jump.
Neoepiblema, described in the magazine Biology Letters, had a large mass but a very small brain.
A digital reconstruction of his brain using CT scans (computed tomography) showed that it was very small and only weighed four grams. A human brain is around 3 pounds.
The skulls of two individuals were found at a fossil site in Acre in the western Brazilian Amazon. One was almost complete and the other contained a fragment of the skull, the part that encloses the brain
Main author Dr. Jose Ferreira said: ‘Neoepiblema was about five feet tall and weighed around 80 kg, which exceeds the capybara (photo), the largest living rodent that is around 60 kg
Dr. Ferreira, of the Federal University of Santa Maria, stated: “The adaptive value of low energy costs and other ecological factors may be associated with the relatively small brain size of giant rodents.
“Although Neoepiblema was one of the largest rodents ever, the brains of this giant rodent were very small in relation to its body mass.
“The evolution over time of this relationship between brain and body size is known as encephalisation.”
To analyze the differences between animals of different body sizes, researchers calculate the encephalisation quotient (EQ).
This is a way to measure the difference between the expected size for an animal of a certain weight and the actual size of the brain.
For example, people have an average EQ of about 6. For most living South American rodents, this is about 1.05. But for Neoepiblema it was around 0.3.
There are more than 2,000 living species of rodents – almost half of the different mammals on Earth.
They include different groups such as porcupines, beavers, squirrels, marmots, pocket gopher and chinchillas.
Dr. Ferreira said: “Some extinct South American members of this clade reached a gigantic body size during the Late Miocene, some 10 million years ago.
‘Neoepiblema acreensis is one of the largest rodents in South America.