An extinct giant ground sloth of the Pliocene and Pleistocene epochs in America, reaching a height of 5 m (16 ft) when standing erect.
- ‘But Cuvier, since then, has fully proved that these so-termed bones of giants were in reality fossil remains of mammoths, megatheriums, mastodons, and similar extinct brutes; and that the giant's teeth’ found in many museums, had once graced the jaw-bones of spermaceti whales.’
- ‘Giant ground sloths, or megatheria, stood up to six meters (three stories) tall and walked North and South America 2,000,000 to 11,000 years ago.’
- ‘In Heuvelmans’ book there is also a chapter propounding the existence of megatheriums, or giant ground sloths, in South America.’
- ‘The suspicion began to arise that perhaps the Cambrian trilobites may not be really any older than the big dinosaurs, and the latter may not have been all killed off when the big elephants and megatheriums roamed around over America and Europe.’
- ‘Several megatheriums and other rare species of the prehistoric era lived on this island.’
Modern Latin, from Greek mega thērion great animal.