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Giant Ground Sloth (Megatherium)

By: Staff

Updated on: 28/03/2022

The Giant Ground Sloth, also known as the Megatherium, was a genus of enormous rhino-sized ground sloths (as opposed to the modern-day tiny tree sloths) that were indigenous to South America and migrated and spread across the entire continent of North America. These large, furry herbivores lived for about 5.3 million years and went into extinction around 10,000 years back.

Scientific Classification


Quick Facts

Geological Period:Pleistocene Era or the Great Ice Age ( 1.8 mya)
Size:Largest specimens grew to about 20 feet in length
Height:12 feet (when reared up on the hind legs)
Weight:Up to 4.4 tons
Average Lifespan:Unknown
Location/Distribution/Range:Skeletal remains have been found from Alaska, Canada’s Northwest Territories, New Mexico, northern Mexico, Arizona, and California, and in the Midwest regions, like in Illinois, Ohio, Kentucky, Missouri, Minnesota, and Tennessee, most fossils of the animals belonging to the genus have been found from inside ancient caves
Habitat:Preferred forests along rivers, lakes, and other water bodies
Climate/Environment:Varied between species
Birth Type (Reproduction):Viviparous
Locomotion:Footprints suggest they were primarily quadruped, but were capable of assuming a bipedal stance (like a bear)

History and Discovery

Giant Ground Sloth

It was in 1796 that the first fossil of a Megatherium (Megatherium americanum) was discovered by the French anatomist Georges Cuvier, the ‘father of paleontology’, who recognized it as a type of ancient sloth.

The oldest recovered fossils belonged to the era 5.4 million years ago; however, the species Megatherium americanum evolved much later, during the Pleistocene period that dates to about 1.8 million years.

Megatherium Fossil
Pictures of a Giant Ground Sloth

According to the Illinois State Museum, numerous fossils of different species of the Megatherium have been unearthed from at least 150 different sites across North America.

Back in the 1830s, scientist Sir Charles Darwin made several discoveries in parts of South America, during an expedition at a tender age, all of which were mysterious remains of extinct mammalians. Among his findings, there were four individual species of giant ground sloths, along with a gomphothere and an ancient horse.


The exact reason for their disappearance is yet not known. However, humans were contemporary to these creatures and are thought to be their primary enemies and predators, responsible for their extinction about 10,000 years ago by hunting them down for food.


The genus had eight species and one type species:

  • Megatherium americanum (type species)
  • Megatherium altiplanicum
  • Megatherium celendinense
  • Megatherium medinae
  • Megatherium istilarti
  • Megatherium parodii
  • Megatherium sundti
  • Megatherium gallardoi
  • Megatherium urbinai

Physical Description

Giant Ground Sloth Size
Giant Ground Sloth Fossil

Unlike the six small, modern tree sloth species, these gigantic beasts dwelled on land and had physical characteristics to suit their ground-dwelling lifestyle. However, interestingly, they were the ancestors of the modern-day sloths only, that weigh less than 20 pounds. They had a low, narrow skull with a minimal amount of brain matter.

Giant Ground Sloth Skeleton

Among all the species, Megalonyx jeffersonii was the largest that had the size of an adult ox, whereas, the Megatherium americanum is the type species. They have stubby legs and long arms, with the entire body covered with yellowish fur. Its skull (head) was blunt with rows of teeth adapted to chewing leaves and plant matter. It had large claws both for defense and, as also to pull down branches of trees. It probably had a long tongue like the modern sloths to assist them in eating.

Behavior and Diet


Numerous bones, fur, and other skeletal remains suggest that the lifestyles and general disposition varied diversely between the species. However, they were naturally peace-loving creatures that would only show aggression when it came to defense.

Picture of Megatherium

They were slow-moving animals, and the diet of these creatures varied according to climatic changes, while the dung samples also showed which plants these animals preferred, like, during the summer months, they would consume desert plants, while in the winter or wet months they would prefer young leaves from trees. Samples of fecal matter also suggest that they preferred berries and fruits, including the avocado.

Interesting Facts

Megatherium Skull
  • The size of these enormous quadruples was exceeded by only a few of the contemporary land mammals like the Indricotherium and several elephant species.
  • Their generic name Megatherium, in Latin, translates to ‘large beast’.

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