A new study found that dog-sized rats lived alongside humans about one to two million years ago.
Researchers found fossils that represent seven species of giant rats, on the island nation of East Timor (officially the Democratic Republic of Timor-Leste).
Judging by the fossils, the biggest rat would have weighed about 11 pounds (5 kilograms), which is about ten times heavier compared with a modern-day rat, Julien Louys, a research fellow and palaeontologist at the Australian National University, said.
Over the course of a few years, the researchers discovered thousands of fossils that belonged to several species of rats. They estimated that the giant rat fossils were 2 to 1 million years old.
Previous findings showed that giant rats existed 46,600 years ago and that they lived together with humans, who butchered the rats and cooked them.
The density of vegetation on the island may have protected the rats, because no significant changes in the rat population were observed after the arrival of humans.
However, on the Canary Islands – which are smaller than East Timor and do not have as much vegetation – the giant rats were quickly whipped out (within a few hundred years) after humans arrived on the islands.
In the end, giant rats’ destiny on East Timor turned out to be similar to that of the rodents on the Canary Island, as they vanished about 1,000 years ago.
Nowadays some giant rat species do exist, but none of them is as big as those found by the researchers on the island of East Timor. In the Philippines, Flores Island in Indonesia, and Papua New Guinea, there are some species of rats that weigh as much as 6.6 pounds (3 kilograms).
During the Pleistocene epoch, the giant rats that roamed the Earth were indeed huge. The Giant hutias that resembled a guinea pig and lived in the West Indies weighed up to 440 pounds (200 kilograms). Castoroides weighed 220 pounds (100 kilograms) and Josephoartigasia monesi – the biggest rat of them all – weighed almost 3,400 pounds (1,542 kilograms).
The findings were presented by Julien Louys at the yearly meeting of the Society of Vertebrate Palaeontology.
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