Editing Nearctic realm (section)

==History==
Although North America and South America are presently joined by the [[Isthmus of Panama]], these continents were separated for about 180 million years, and evolved very different plant and animal lineages. When the ancient supercontinent of [[Pangaea]] split into two about 180 million years ago, North America remained joined to [[Eurasia]] as part of the supercontinent of [[Laurasia]], while South America was part of the supercontinent of [[Gondwana]]. North America later split from Eurasia. North America has been joined by land bridges to both [[Asia]] and South America since then, which allowed an exchange of plant and animal [[species]] between the continents, the [[Great American Interchange]].

A former land bridge across the [[Bering Strait]] between Asia and North America allowed many plants and animals to move between these continents, and the Nearctic realm shares many plants and animals with the [[Palearctic]]. The two realms are sometimes included in a single [[Holarctic realm]].

Many large animals, or [[megafauna]], including [[horse]]s, [[camel]]s, [[tapir]]s, [[mammoth]]s, [[mastodon]]s, [[ground sloth]]s, sabre-tooth cats (''[[Smilodon]]''), [[Tremarctinae|short-faced bears]] and the [[American cheetah]], became extinct in North America at the end of the [[Pleistocene]] epoch (ice ages) in what is called the [[Quaternary extinction event]].