The Giant Ground Sloth: Everything You Wanted to Know

giant ground sloth illustration

The giant ground sloth, or the Megatherium americanum, is the largest bipedal mammal ever to walk the earth! This gigantic mammal was the ancestor of our current-day sloths and was larger than life. 

There are six living species of sloths today, and they are known to be small and slow. Their distant ancestors, however, were quite the opposite. Some of them were grass grazers, others were burrowers, and some even spent time swimming in the ocean. 

It is hard to believe these vast creatures once roamed our world. In this article, we will teach you everything you need to know about the Giant Ground Sloth. 

When Was The Giant Ground Sloth Alive?

Fossils of the ground sloth have shown that it was alive in the Pleistocene Period, and likely lived through the Holocene's beginning, which started approximately 11,700 years ago. 

They lived during the Ice Age, but experts believe that the ground sloths walked the earth when humans were alive. There have been fossils found that show cut marks, indicating that a human had hunted the creature. Searches discovered one fossil with 41 odd cuts that appear to have been caused by a human-made tool.

Experts believe that they originated in South America and migrated into North America around 8 million years ago. Around the end of the Ice Age, the sloths began to die off. It is not known exactly when they went extinct, though. 

Nobody knows the exact reason they went extinct, either. Some believe that it was due to the climatic changes at the end of the Ice Age, altering their food sources. Others believe that predation and destruction of habitats could have been the cause. Another possible explanation would be that a disease had wiped out many large mammals during this time. 

skeleton of giant ground sloth

When Was the Giant Ground Sloth Discovered?

The first giant ground sloth skeleton was discovered in 1788 by a man named Manuel Torres in Argentina. He gave it the name Megatherium americanum, meaning “great beast from America''. Other fossil records have indicated that it lived in Argentina, Uruguay, and Bolivia. 

Scientists found footprints from this ancient creature in Argentina, near the same site that Charles Darwin collected species in the 1830s.

What Was The Giant Ground Sloth Like?

Although it is related to the sloths we see today, the giant ground sloth is unlike any mammal we have ever seen. 


The giant ground sloth was the largest bipedal mammal that has ever existed, meaning that it walked on two legs, unlike today's sloths, which are arboreal and live in trees. It was also ten times larger than the sloths that we know today and could weigh up to four tons, which is about an elephant’s size. 

They were very tall, standing up to 12 feet. In comparison, present-day sloths are, on average, around 2 feet long and weigh less than 14 pounds. 


The giant ground sloth did have long claws but only used them to eat leaves and fruits. Based on the dental analysis and chemical testing, the sloths were vegetarians. They had peg-like teeth perfect for eating greenery and curved claws that aided in their foraging and stripping branches. 

Scientists found remnants of a dung ball near a preserved giant ground sloth in the 1920s, and analysis showed that it had eaten a diet of cacti, fruits, yuccas, and saltbushes. This particular sloth had climbed into a volcanic gas vent and died, which mummified its body and its dung, allowing us to discover more about its diet. 

Giant ground sloths are also known for their seed spreading abilities. They were large enough to eat avocados entirely, and they would disperse their seeds with their excrement. 


The giant ground sloths lived mostly in forests and around rivers or lakes. They also lived during the Ice Age, where ice and snow covered a majority of the Earth. They were able to endure this freezing climate. 

Scientists believe that they lived all over South America and North America. Some fossil evidence has even been found as far north as Canada and Alaska. They were truly a wide-spread species.

Giant Ground Sloth Fun Facts

These sloths are an incredibly interesting species. We've put together a list of fun facts to help you learn a little more about them.

1) Interestingly, Thomas Jefferson discovered one specific species of the giant ground sloth. The president was interested in fossils, and his friend sent him the mysterious bones that he had found in a cave in West Virginia.

Jefferson initially believed that the bones belonged to a giant lion, which he named the “Great Claw.” He later came to discover, however, that it was no lion at all. As he prepared a paper on the bones to submit to the American Philosophical Society, he came across a sloth skeleton engraving and realized that he had it all wrong. 

He changed his classification and found the bones actually belonged to a species of the extinct giant ground sloth. It was given the name Megalonyx jeffersonii, in honor of Thomas Jefferson.

2) Another fun fact is that the ground sloths, although bipedal, also spent time walking on all fours. The ground sloths have are divided into four different families, and the Megalonychidae are the only ones that stood flat on their rear feet all of the time. Sloths from the other three families known as Megatheriidae, Mylodontidae, and Nothrotheriid walked on their feet' outer sides.

3) The Mylodontidae family of sloths, who lived between Washington and Florida, had a series of bony discs below their skin known as osteoderms. They served as protective armor to these sloths, and they were around the back, neck, and shoulders. Many dinosaurs also had these osteoderms, as do armadillos and crocodiles.

4) One genus of the giant ground sloth spent much of its time in the ocean. They had hooked claws to help them grip onto seaweed and rocks and pull themselves down to eat algae in the sea. They had dense ribs and bones, making them less buoyant than the other Ground Sloth species.

5) Scientists believe that some of the Mylodontidae might have been excellent diggers because of their flattened claws. Ancient tunnels throughout Argentina led some scientists to believe that the giant ground sloths may have even been a ground burrowing animal. They found scratch marks in these huge tunnels that match this family of giant ground sloths’ claws.

6) Some scientists believe that the giant ground sloths were around long after the Ice Age drove most of them to extinction. Some radiocarbon from fossils indicates that they may have lived in Hispaniola and Cuba as recently as 4,200 years ago. 

Final Thoughts

Over 100 different giant ground sloth species once roamed the earth, and although we will never be able to experience these gigantic beasts, their legacy is carried on through modern-day sloths. Since they were the size of elephants and had long, curved claws, maybe it is best that we can only observe them in museums!