Late Pleistocene extinctions in the context of "Hippidion"

Xenarthra (/zɛˈnɑːrθrə/; from Ancient Greek ξένος (xénos), meaning "strange, foreign", and ἄρθρον (árthron), meaning "joint") is a superorder and major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and armadillos. Extinct xenarthrans include the glyptodonts, pampatheres and ground sloths, with some glyptodonts and ground sloths reaching sizes of several tonnes, much larger than any living xenarthran. Xenarthrans originated in South America during the late Paleocene about 60 million years ago. They evolved and diversified extensively in South America during the continent's long period of isolation in the early to mid Cenozoic Era. They spread to the Antilles by the early Miocene and, starting about 3 million years ago, spread to Central and North America as part of the Great American Interchange. Nearly all of the formerly abundant megafaunal xenarthrans became extinct at the end of the Pleistocene as part of the end-Pleistocene extinction event.

The woolly rhinoceros (Coelodonta antiquitatis) is an extinct species of rhinoceros that inhabited northern Eurasia during the Pleistocene epoch. The woolly rhinoceros was large, comparable in size to the largest living rhinoceros species, the white rhinoceros (Ceratotherium simum), and covered with long, thick hair that allowed it to survive in the extremely cold, harsh mammoth steppe. It had a massive hump reaching from its shoulder and fed mainly on herbaceous plants that grew in the steppe. Mummified carcasses preserved in permafrost and many bone remains of woolly rhinoceroses have been found. Images of woolly rhinoceroses are found among cave paintings in Europe and Asia, and evidence has been found suggesting that the species was hunted by humans. Like other Pleistocene megafauna, the species became extinct as part of the end-Pleistocene extinction event. The range of the woolly rhinoceros contracted towards Siberia beginning around 17,000 years ago, with the youngest reliable records being around 14,000 years old in northeast Siberia, coinciding with the Bølling–Allerød warming, which likely disrupted its habitat, with environmental DNA records possibly extending the range of the species around 9,800 years ago. Its closest living relative is the Sumatran rhinoceros (Dicerorhinus sumatrensis).

Notoungulata is an extinct order of ungulates that inhabited South America from the early Paleocene to the end of the Pleistocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resembling animals as disparate as rabbits and rhinoceroses. Notoungulata are the largest group of South American native ungulates, with over 150 genera in 14 families having been described, divided into two major subgroupings, Typotheria and Toxodontia. Notoungulates first diversified during the Eocene. Their diversity declined from the late Neogene onwards, with only the large toxodontids persisting until the end of the Pleistocene (with Mixotoxodon expanding into Central America and southern North America), perishing as part of the Late Pleistocene megafauna extinctions along with most other large mammals across the Americas. Collagen sequence analysis suggests that notoungulates are closely related to litopterns, another group of South American ungulates, and their closest living relatives being perissodactyls (odd-toed ungulates), including rhinoceroses, tapirs and equines as part of the clade Panperissodactyla. However their relationships to other South American ungulates are uncertain. Several groups of notoungulates separately evolved ever-growing cheek teeth.

Homotherium is an extinct genus of scimitar-toothed cat belonging to the extinct subfamily Machairodontinae that inhabited North America, Eurasia, and Africa, as well as possibly South America during the Pliocene and Pleistocene epochs from around 4 million to 12,000 years ago. A probable descendant of Amphimachairodus, it was one of the last surviving members of Machairodontinae alongside the more famous sabertooth Smilodon, to which it was not particularly closely related. It was a large cat, comparable in size to a lion with a body mass of up to 200 kilograms (440 lb), functioning as an apex predator in the ecosystems it inhabited. It had an elongate neck and relatively elongate legs, a relatively short back and a very short tail, with the mummy of a H. latidens cub of Late Pleistocene age found in Siberia having a plain dark brown coat colour. In comparison to Smilodon, the canines of Homotherium were shorter, though still longer than those of living cats, and it is suggested to have had a different ecology from Smilodon as a moderate speed endurance pursuit predator adapted to running down large prey, such as antelope, equines, bovines, and juvenile mammoths in open habitats, with Homotherium also proposed to have likely engaged in cooperative hunting.

Once widely distributed over most of the world's continents, the genus saw a protracted decline over the course of the Pleistocene, disappearing from Africa during the Early Pleistocene around 1.5 million years ago, and declining in abundance and distribution in Eurasia during the Middle Pleistocene, though with a handful of records in the Late Pleistocene. In North America, the genus survived until the end of the Late Pleistocene around 12,000 years ago, becoming extinct as part of the end-Pleistocene extinction event along with most other large animals native to the Americas. This followed the arrival of humans into the Americas, who may have caused a decline in populations of large prey on which Homotherium depended.