The giant sloths, also referred to as the ground sloths, belong to an interesting group of animals found in southern North America, Central America and South America. This group is the "edentate" animals. The name means "toothless," but this is misleading as these animals all have teeth. They are just missing their front teeth and have cheek teeth that are often reduced in size. Other members of the edentates are the armadillos, glyptodonts, and modern tree sloths.
The giant sloths first appeared in South America in the Early Oligocene Epoch (36 to 22.5 million years ago), and they survived up until recent times, only becoming extinct during the Pleistocene Epoch (1.8 million years ago to 10,000 years ago), during the last Ice Age. From the Miocene Epoch (22.5 to 5 million years ago), the sloths diverged into two different forms: the giant ground sloths and the smaller tree-dwelling sloths which survive today. During the Pliocene Epoch (5 to 1.8 million years ago), sloths were able to spread from South America across Central America and widely into North America via the Panamanian isthmus.
The giant sloths were herbivorous (plant-eating), slow-moving animals. They had short, stumpy tails that could be used as a prop to help them rear up onto their hind legs in order to reach tree branches. Their forearms were extremely powerful with massive manuses ("hands") with large claws which could be used to rip branches from trees. Their hind legs were also powerful to support their great weight when they reared up. We know that they liked to feed on leaves and twigs, the same as modern tree sloths, because coprolites from ground sloths have been found in North and South America.
Due to their slow gait, the giant sloths might have been easy prey to some of the Pleistocene Epoch predators, but their powerful forearms and large claws would have been formidable defensive weapons. They also had very thick skin, toughened by tiny nodules of embedded bone called "ossicles." Samples of giant sloth skin have been found in southern South America.
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