Quaternary extinction event in the context of "Sloth"

Haringtonhippus is an extinct genus of equine from the Pleistocene of North America The genus is monospecific, consisting of the species H. francisci, initially described in 1915 by Oliver Perry Hay as Equus francisci. Members of the genus are often referred to as stilt-legged horses, in reference to their slender distal limb bones, in contrast with those of contemporary "stout legged" caballine true horses.

Haringtonhippus fossils have only been discovered in North America. Specimens have been found from southern Mexico to southern South Dakota and in Alberta, Canada, at sites such as Gypsum Cave and Natural Trap Cave, as well as eastern Beringia in Yukon A later study found that Equus cedralensis from the Late Pleistocene of Mexico also belonged to this species. The earliest species of the lineage appeared in North America during the Late Pliocene to Early Pleistocene, around 2 to 3 Ma. It became extinct at the end of the Late Pleistocene, around 12,000 years ago as part of the end-Pleistocene extinctions, along with most other large mammals in the Americas.

Cingulata, part of the superorder Xenarthra, is an order of armored New World placental mammals. The armadillos, whose species are split between the families Dasypodidae and Chlamyphoridae, are the only surviving members of the order. Two groups of cingulates much larger than extant armadillos (maximum body mass of 45 kg (100 lb) in the case of the giant armadillo) existed until recently: pampatheriids, which reached weights of up to 200 kg (440 lb) and chlamyphorid glyptodonts, which attained masses of 2,000 kg (4,400 lb) or more.

The cingulate order originated in South America during the Paleocene epoch about 66 to 56 million years ago, and due to the continent's former isolation remained confined to it during most of the Cenozoic. However, the formation of a land bridge allowed members of all three families to migrate to southern North America during the Pliocene or early Pleistocene as part of the Great American Interchange. After surviving for tens of millions of years, all of the pampatheriids and giant glyptodonts apparently died out during the Quaternary extinction event at the beginning of the Holocene, along with much of the rest of the regional megafauna, shortly after the colonization of the Americas by Paleo-Indians.