New (but extinct) species of Giant Sloth discovered

An underground cave in Yucatan, Mexico, has given rise to the discovery of an extinct species of giant sloth.

While cliff-diving in Mexico, Vicente Fito made a remarkable discovery: the preserved skull and several bones of a sloth. That might not sound like much, but the discovery was remarkable for a few reasons. Firstly, Fito was deep in the hot and humid jungles of Yucatan, where preserved remains are rare. Usually, animal remains would rot in the heat but this cave provided shelter from harsh conditions. The second remarkable thing was that the bones would have belonged to a sloth weighing at least 500-pounds. No species of giant sloth is alive today and, in fact, modern sloths weigh well under 20-pounds. What’s more, these fossils of an extinct giant sloth, just lying in a cave, are over 10,000 years old. This has allowed experts to speculate when sloths must have migrated to North America around this time.

modern small sloth giant sloth
Today’s sloths are quainter than their ancient ancestors.

The oldest recorded fossil of a sloth is over 9 million years old and comes from Argentina, so this find provides researchers with a great insight into when and where sloths managed to spread northwards. Narrowing a 9 million year gap is a huge boon to research on sloths and their development. That, however, is not the last remarkable thing about this discovery. The skull and bones belonged to an entirely new species of giant sloth. That is, new, despite being thousands of years old. The previously unknown species has been named Xibalbaonyx oviceps and it’s in good company. While a speculated 500-pounds sounds incredibly large for a sloth, it’s not so impressive compared to other giants. A truly giant sloth called Megatherium, which used to take up its fair share of South America during the Pleistocene Period, rivaled elephants in size and weighed around 4 tons.

Megatherium, a truly giant sloth. (Image sourced from Encyclopedia Britannica)
Megatherium (Image sourced from Encyclopedia Britannica)

Unravelling the past

Despite our ability to travel around the globe with ease, we’re still discovering how little we know about our own world and its rich history. Xibalbaonyx oviceps was found years ago and only recently classified, but other ancient discoveries are taking place all the time. Only a matter of weeks ago, National Geographic and BBC were reporting on the discovery of not one, but two, species of Jurassic flying squirrels discovered in China. And, of course, there’s the recent discovery of an entirely new species of dinosaur, proving just how much we still have to discover about the Earth we walk across and just how many wild and wondrous creatures roamed this world before us. We only even know that the giant ape Gigantopithecus ever existed because of its jawbone. It wasn’t an archeological dig that uncovered the jawbone either. Someone in China was apparently selling it as medicine.

Gigantopithecus was long gone thousands of years ago (but we can pretend one stuck around to be in The Jungle Book.)
Gigantopithecus was long gone thousands of years ago (but we can pretend one stuck around to be in The Jungle Book.)

We can’t always expect luck to help us discover the amazing things in our world. We need to continue exploring the planet and its past with wonder. Who knows what incredible creatures are just waiting for us to rediscover their place in history?

Ronan Daly

Ronan Daly is a staff writer for My Good Planet who specialises in Technology and Science. With a Masters Degree in English, and over a decade's experience as a teacher and writer, Ronan has brought a breezy, learned style to My Good Planet, making occasionally complex material accessible and understandable to all.