Sloth, related to slow, literally means "laziness," and their common names in several other languages (e.g.
Sloths are so named because of their very low metabolism and deliberate movements. They included both ground and arboreal forms which became extinct after humans settled the archipelago in the mid-Holocene, around 6,000 years ago. Members of an endemic radiation of Caribbean sloths formerly lived in the Greater Antilles. The extinction correlates in time with the arrival of humans, but climate change has also been suggested to have contributed. However, they became extinct during the Quaternary extinction event around 12,000 years ago, together with most large bodied animals in the New World. Besides the extant species, many species of ground sloths ranging up to the size of elephants (like Megatherium) inhabited both North and South America during the Pleistocene Epoch. The two groups of sloths are from different, distantly related families, and are thought to have evolved their morphology via parallel evolution from terrestrial ancestors. Despite this traditional naming, all sloths actually have three toes on each rear limb, although two-toed sloths have only two digits on each forelimb. There are six extant sloth species in two genera – Bradypus (three–toed sloths) and Choloepus (two–toed sloths). They are considered to be most closely related to anteaters, together making up the xenarthran order Pilosa. Noted for their slowness of movement, they spend most of their lives hanging upside down in the trees of the tropical rainforests of South America and Central America. Sloths are a group of arboreal Neotropical xenarthran mammals, constituting the suborder Folivora. Level 3 airports are under slot control and require advance approval to operate during slot controlled hours.Temporal range: Early Oligocene to Holoceneĭelsuc, Catzeflis, Stanhope, and Douzery, 2001 Level 3 airports have demand for airport infrastructure that significantly exceeds the airport's capacity during the relevant periods and without controls, would have unacceptable systemic delays.
Level 2 airports may have some periods when demand approaches one or more capacity limits, but a voluntary schedule-facilitation process prevents systemic delays. Level 1 airports have sufficient capacity to meet demand. Slots, or limits on the planned aircraft operations, are a tool used in the United States and around the world to manage air traffic at extremely busy airports, and to prevent repeated delays that result from too many flights trying to take off or land at the same time.Īround the world, airports are designated at levels indicating their degree of congestion. This authorization is for a planned aircraft operation and is distinct from air traffic control clearance or similar authorizations. In the context of airport coordination, a slot is an authorization to either take-off or land at a particular airport on a particular day during a specified time period.
#SLOTH DEFINITION SERIES#
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