The Nearctic is one of the eight major biogeographic regions of the world.
It covers almost the entire North America, Greenland and the highlands of Mexico. Southern Mexico, South Florida, Central America and the Caribbean islands belong together with South America to Neotropics.
North and South America, which are now joined at the Isthmus of Panama, were separated before about 180 million years ago and thus developed very different types of plants and animals. At the breakup of the supercontinent Pangaea North America remained connected with Eurasia, and thus became part of the newly created northern supercontinent Laurasia, while South America was part of the southern supercontinent Gondwana. By the opening of the Atlantic Ocean to North America and Europe separated.
North America was later connected by land bridges to Asia ( Bering Strait ) and South America ( Panama). This allowed an exchange of species between the continents, known as the Great American Interchange ( Great American Interchange).
Thus, the Nearctic and Palearctic the share a variety of animal and plant species. The two biogeographic regions are therefore also connected to a common Holarctic region.
Many large animals, such as Horses, camels, mammoths, mastodons, early bison, saber-toothed tigers and short-faced bears, died out at the end of the Ice Age. At the same time the settlement began by humans. Scientists believe that not of climate change, but the extinction caused by the hunting of man and the consequent shortage of food for predators species extinction.
Besides humans but could the modern American Bison, the grizzly bear and the elk through the vacant ecological niches foothold.
Originally the dogs came ( Canidae ), the camels ( Camelidae ) and horses ( Equidae) only in the Nearctic ago. The Paarhuferfamilie the fork Bovidae ( Antilocapridae ) always remained limited to this region.
The cheetah originally evolved in North America and only came to Europe and later to Asia and is now only found in Africa. The short-faced bear lived only in North America. The only surviving member of this family is still living today in South America spectacled bear.