Extinct Rodents Of Unusual Size Found In Philippine Cave

New fossils suggest that giant cloud rats roamed the Philippines and lived alongside ancient humans for over 60,000 years.

AsianScientist (Apr. 27, 2021) – While oversized rodents are typically the stuff of nightmares, new fossil remains indicate that giant cloud rats lived in the Philippines for over 60,000 years alongside ancient humans. The discovery, made by a joint Philippine-US team, was detailed in the Journal of Mammalogy.

In the 1987 cult classic film The Princess Bride, a memorable scene sees the two protagonists journeying through the dangerous Fire Swamp. Along the way, they quickly encounter the legendary ‘rodents of unusual size’—monstrous, rat-like creatures with an uncanny sense for blood.

It turns out that these rodents did exist—at least in ancient Philippines. Known as ‘cloud rats,’ the giant mammals lived in the treetops of misty mountain forests. However, unlike their fictional counterparts, cloud rats were much cuddlier, filling an ecological niche similar to that of squirrels in the US.

“We have had evidence of extinct large mammals on the Philippine island of Luzon for a long time, but there has been virtually no information about fossils of smaller-sized mammals,” explained lead author Ms. Janine Ochoa, an Assistant Professor of Archaeology at the University of the Philippines Diliman.

Much like other great scientific moments, the team discovered the cloud rat fossils serendipitously. Ochoa and her team had been examining fossil remains in the Philippines’ Callao Cave, where a new species of ancient human—Homo luzonensis—had been identified in 2019.

“We were looking at the fossil assemblages associated with that hominin, and we found teeth and fragments of bone that ended up belonging to these new species of cloud rats,” said Ochoa.

To make things even more challenging, the researchers had only fifty or so fossil fragments to work with—most of which were teeth. However, from just a few dozen teeth and bits of bone, the team managed to find three new species of cloud rat and piece together a picture of how they might have lived.

“The bigger ones would have looked almost like a woodchuck with a squirrel tail,” said Dr. Larry Heaney, co-author and curator at Chicago’s Field Museum. “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.”

Some specimens of the new fossil rodents were found in the same deep layer in the cave where H. luzonensis was found, dated at about 67,000 years ago. However, some specimens were also found in layers that date back to just 2,000 years ago or later—indicating that these giant cloud rats were hardy creatures that persisted for at least 60,000 years.

While the cloud rats may have survived the Ice Age and other major climatic changes, their final extinction may have ultimately been caused by humans. After all, their abrupt disappearance in the fossil record coincides with the era when pottery, Neolithic stone tools and domesticated animals first appeared in the Philippines.

The team’s discovery ultimately paves the way for future studies investigating the impact of human activities on biodiversity—an especially relevant topic in a world increasingly shaped by mankind.

“Our discoveries suggest that future studies that look specifically for fossils of small mammals may be very productive, and may tell us a great deal about how environmental changes and human activities have impacted the really exceptionally distinctive biodiversity of the Philippines,” concluded Ochoa.

The article can be found at: Ochoa et al. (2021) Three new extinct species from the endemic Philippine cloud rat radiation (Rodentia, Muridae, Phloeomyini).

Source: Field Museum. Photo: Velizar Simeonovski.
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