Fossil remains of the skull of a giant extinct rodent that lived 10 million years ago in South America, indicate that it measured 1.5 meters and weighed 80 kilos, but its brain barely weighed 113 grams. The find, presented in ‘Biology Letters’ by researchers from the Brazilian universities of Acre and Federal de Santa María, and the Paleontological Museum and Institute, describes the largest rodent ever known in South America, which has been called ‘Neoepiblema acreensis’.
The almost complete skull was in very good condition, it was so well preserved that researchers were able to distinguish the impressions produced by olfactory bulbs, which are parts of the brain involved in the processing of odors. They could also see where the frontal and temporal lobes had been.
By looking at the size of the skull, the researchers were able to calculate the total probable size of the rodent. They estimate that the creature was approximately 1.5 meters long and weighed approximately 80 kilograms, which made it approximately the size of an adult human being. It also had very large incisors.
A subsequent study dated the remains in approximately 10 million years.
They also discovered that the creatures were extinct relatives of modern pecans and chinchillas and that they lived in the western part of the Brazilian Amazon. At that time, before the area was a rainforest, it was a swamp, and South America was still isolated from North America and Antarctica. The researchers also point out that due to its large size, it was probably not the goal of many predators, although it would have been a good meal for the giant crocodiles that lived in the area during the same period of time.
They also assume that he was probably not very intelligent: his brain was small compared to the rest of his body, weighing only 113 grams.