Scientists have discovered that large rats the size of dogs once roamed the Earth.

Although they are already extinct, it is still possible that the gigantic versions of these rats and other animals could return.

The discovery was made by researchers led by Dr. Julien Louys from the Australian National University School of Culture, History and Language. They presented their findings during the Meetings of the Society of Vertebrate Palaeontology event recently held in Texas, Discovery News has learned.

According to Louys, these rats, which were ten times bigger than modern rodents, thrived in East Timor about 46,000 years ago.

"They are what you would call mega-fauna," he said in a statement according to the Business Standard. "The biggest one is about five kilos, the size of a small dog. Just to put that in perspective, a large modern rat would be about half a kilo."

The researchers explained that these giant rats co-existed with the early humans for about one thousand years before going extinct. Based on their findings, these animals were wiped out due to two major factors.

First, they found evidence that the early humans ate these giant rats. The researchers made this conclusion after seeing burn marks on bones of some of samples they collected. This suggests that the humans cooked the rats first before eating them.

Another major factor that's responsible for the extinction of the large rodents is the discovery of metal tools. According to the researchers, these items made the early humans more efficient in their daily activities. However, these also led to wide-scale deforestations which directly affected the natural habitat of the animals.

"The funny thing is that they are co-existing up until about a thousand years ago," Louys said in a press release. "The reason we think they became extinct is because that was when metal tools started to be introduced in Timor, people could start to clear forests at a much larger scale."

But, even though these large rats are already extinct, there is still a chance that these animals, and others that share the same distinct size, could make a comeback in the future. As Christian Science Monitor pointed out, after the large fauna, particularly the dinosaurs, died out millions of years ago, it took more than 10 million years before large animals emerged and roamed the Earth once again.

Following the same trend, it's possible that future generations will encounter living rats the size of small dogs.