THE FINAL days of a giant sloth that stood once stood four metres tall have been revealed – thanks to the discovery of an enormous tooth.
A partly fossilised tooth belonging to the gigantic beast was unearthed from a deep sinkhole in Belize, where it’s believed to have “taken its final drink”.
Experts believe described the creature – which lived some 27,000 years ago – as “thirsty”.
That’s because the Last Glacial Maximum had “locked up” much of the Earth’s moisture in glaciers and polar ice caps.
It also meant that water tables in the local area were low, making it difficult for the enormous sloth to quench its thirst.
So the sloth took its last sip of a liquid in a “deep sinkhole with steep walls down to the water”.
The sloth was discovered after divers found some of its remains during a search for ancient Mayan artifacts in the pool.
They uncovered parts of a tooth, humerus and femur belonging to the giant sloth.
Researchers say the tooth has partially fossilised, but still had enough “unaltered tissue” for analysis, giving up clues about what the sloth ate in the last year of its life.
This allowed experts to learn more about the local climate and environment at the time too, which was revealed in the Science Advances journal.
“We began our study with the hopes of gaining a better understanding of the landscape within which large mammals went extinct and humans emerged in central Belize,” said Jean T. Larmon, of the University of Illinois, who led the study.
“In the process, we discovered which part of the tooth had best maintained its integrity for analysis.
“And we refined methods for studying similar specimens in the future.”
Lisa Lucero, an anthropology professor at the university, said that the discovery adds to the evidence that “many factors, in addition to a changing climate, contributed to the extinction of megafauna in the Americas”.
“One of those potential factors is the arrival of humans on the scene 12,000 to 13,000 years ago,” she added.
Giant sloths – the key facts
Here's what you need to know…
- Megatherium is the official name for a genus of elephant-sized ground sloths native to South America
- They’re better known as giant growth sloths, and lived from the early Pliocene, an epoch that began 5.333million years ago
- Sadly, giant sloths became extinct roughly around 8,500 BC
- There were only a few other land mammals that were bigger than Megatherium, making them one of the world’s most interesting megafauna
- The first fossil specimen of Megatherium was discovered in Argentina in 1788
- Since then, more fossils have been found across South America, including in Argentina, Bolivia, Brazil, Chile, Colombia, Guyana, Paraguay, Peru and Uruguay
- They’re one of the biggest land mammals known to have ever existed
- They could weigh up to 4 tonnes, and measured up to 6 metres (20 foot) in length
- The creatures were herivorous, and had huge curved claws for pulling down far-away branches
- Giant sloths largely walked on all fours, but trackways reveal that they were capable of walking on two legs at times too
The giant sloth’s tooth is different from those found in other large mammals, like mammoths, that went extinct between 14,000 and 10,000 years ago.
“Giant sloth teeth have no enamel, the hard, outer layer of human and some animal teeth that can be analysed to learn about their diet,” Larmon explained.
These giant sloths have been difficult to study generally, because they’re mostly fossilised, with minerals replacing original tissue.
But using a special technique that makes minerals glow, researchers were able to find one type of tooth tissue that was intact.
Larmon drilled 20 samples of this tissue for analyst along the 10cm-long tooth fragment, which spanned more than a year of tooth growth.
“This allowed us to trace monthly and seasonal changes in the sloth’s diet and climate for the first time, and also to select the best part of the tooth for reliable radiocarbon dating,” said Stanley Ambrose, an anthropology professor at the University of Illinois.
Researchers were able to prove that the giant sloth lived through a long and dry season that lasted about seven months.
This period was “sandwiched” between two short rainy seasons.
Analysis also revealed that the creature lived in a savanna rather than a forest, and consumed lots of different plants depending on whether it was a wet or dry season.
“We were able to see that this huge, social creature was able to adapt rather readily to the dry climate, shifting its subsistence to relying upon what was more available or palatable,” Larmon said.
And Lucero added: “This supports the idea that the sloths had a diverse diet.
“That helps explain why they were so widespread and why they lasted so long.
“It’s likely because they were highly adaptable.”
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