Fossils Show Ancient Rats Were the Size of a Small Dog

And our ancient ancestors likely ate them

giant rat bones
Researcher Julien Louys holds the jaw bone of an ancient giant rat species discovered in East Timor (left) and the same bone from a modern rat (right) Stuart Hay, Australian National University

Compared to their mousy cousins, rats are sure to surprise with their size. They can grow large enough to drag a whole slice of pizza. But modern rats are just a tenth the size of rats that once cavorted around East Timor, reports Rachel Feltman for The Washington Post

Researchers found the fossils of seven giant rat species that lived in the Southeast Asian island nation. The largest of these weighed about 11 pounds, compared to today’s large rats that top out at about two. The fossils date back to about 44,000 years ago, the researchers reported this week at the 75th Annual Meeting of the Society of Vertebrate Paleontology

They would have been the size of a small dog, says lead research Julien Louys of Australian National University, reports John Ross for The Australian. The fossils also reveal that their large size did not deter human hunters.

"As soon as humans got there they started catching and eating these guys," Louys says. The earliest evidence of humans in the area dates back to 46,000 years ago. "Almost all the remains show some sign of burning. People were catching these rats and sticking them in the fire, then eating them pretty much as is."

Just as settlers did for the large rice rats of the Caribbean, humans would vanquish the rats of East Timor, according to a press release from the Australian National University. Yet it wasn’t the humans’ culinary mores that brought the species’ downfall but a rather more disruptive habit they had of chopping down trees. The giant rats endured human predation for centuries, but about 1,000 years ago the last one died. That time coincides with the introduction of metal tools to East Timor. "People could start to clear forests at a much larger scale," Louys says in the press release.

This ancient species’ size makes them the largest rats to have ever existed. The only species that might try to contend this are distant relatives of true rats and don’t even come close. Giant pouched rats of sub-Saharan Africa are sometimes called "cat-sized," but "kitten-sized" might be more apt: The rodents typically weigh only two to three pounds. Their ability to sniff out landmines or tuberculosis might be impressive, but to the ancient rats of East Timor, their size wouldn’t have been.

The researchers did not comment on just how large a pizza these ancient rodents could have snatched.

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