Scientists have unearthed the 67,000-year-old fossilized remains from three species of giant cloud rats in several caves on the Philippine island of Luzon.

According to a new study published Friday in the Journal of Mammalogy, the three newly-discovered species of cloud rats, Crateromys ballikCarpomys dakal, and Batomys cagayanensis, are thought to be extinct. 

“We were looking at the fossil assemblages associated with that hominin,” said Janine Ochoa, an archaeologist at the University of the Philippines in Diliman, in a Field Museum press release. “And we found teeth and fragments of bone that ended up belonging to these new species of cloud rats.”

Cloud rats began diversifying in the region some 14 million years ago, when their ancestors first arrived in the Philippine archipelago from the Asian mainland. Modern members of the group can weigh up to six pounds and be nearly three feet long from nose to tail.

“The bigger ones would have looked almost like a woodchuck with a squirrel tail,” said Larry Heaney, the Curator of Mammals at the Field Museum, in the same press release. “Cloud rats eat plants, and they’ve got great big pot bellies that allow them to ferment the plants that they eat, kind of like cows. They have big fluffy or furry tails. They’re really quite cute.”

“Approximately two to three thousand years ago, they disappeared. And the obvious question is, why?” Heaney said. “We know enough now to ask that question. Until we discovered these things, we didn’t know there was a question to be asked.”