Megatheriidae is a family of

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

ground sloths that lived from approximately 23 mya—11,000 years ago. Megatheriids appeared during the Late Oligocene ( Deseadan in the SALMA classification), some 29 million years ago, in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. The group includes the largest known ground sloths, the elephant sized '' Megatherium'' (given its name 'great beast' by

Georges Cuvier Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...

) and ''

Eremotherium ''Eremotherium'' (from Greek for "steppe" or "desert" "beast": ἔρημος "steppe or desert" and θηρίον "beast") is an extinct genus of giant ground sloth in the family Megatheriidae. ''Eremotherium'' lived in southern North America, Cen ...

''. An early genus that was originally considered a megatheriid, the more slightly built '' Hapalops'', reached a length of about . The nothrotheres have recently been placed in their own family, Nothrotheriidae. The skeletal structure of these ground sloths indicates that the animals were massive. Their thick

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

s and even thicker

joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

s (especially those on the hind legs) gave their appendages tremendous power that, combined with their size and fearsome claws, provided a formidable defense against predators. The earliest megatheriid in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

was '' Sibotherium'' which arrived 5.3 million years ago, after crossing the recently formed

Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...

nian land bridge. At more than five tons in weight, in length, and able to reach as high as , ''

'' when fully erect was taller than an African bush elephant bull. Unlike relatives, this species retained a

plesiomorph In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral Phenotypic trait, character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorph ...

ic extra claw. While other species of ''Eremotherium'' had four fingers with only two or three claws, ''E. eomigrans'' had five fingers, four of them with claws up to nearly long.De Iuliis and Cartelle (1999)

Phylogeny

The following phylogeny is based on Varela ''et al''. 2019.

References

External links

*
CTD: Megatheriidae

Memidex: Megatheriidae
{{Taxonbar, from=Q784732 Prehistoric mammal families Burdigalian first appearances Holocene extinctions Neogene mammals of South America Neogene mammals of North America Pleistocene mammals of South America Pleistocene mammals of North America Taxa named by John Edward Gray