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The Nearctic ecozone covers most of North America, including Greenland and the highlands of Mexico. Southern Mexico, southern Florida, Central America, and the Caribbean islands are part of the Neotropic ecozone, together with South America.
Although North America and South America are presently joined by the Isthmus of Panama, these continents were separated for tens of millions of years, and evolved very different plant and animal lineages. When the ancient supercontinent of Pangaea split into two 200 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 AsiaThe continent of Asia is defined by subtracting Europe and Africa from the great land mass of Africa-Eurasia. The boundaries are vague, especially between Asia and Europe: Asia and Africa meet somewhere near the Suez Canal. The boundary between Asia and E and South America since then, which allowed an exchange of plant and animal speciesThis article discusses biological species. Also see combinatorial species for the mathematical meaning of the term. Species is also a movie by Roger Donaldson. In English "species" is both singular and plural. The word " specie" is unrelated and is used t between the continents.
A former land bridge across the Bering StraitThe Bering Strait is a sea strait between Cape Dezhnev, the eastmost point of the Asian continent and Cape Prince of Wales, the westernmost point of the American continent, about 85 km in width, with a depth of 30 50 m. The strait connects the Chukchi Sea between Asia and North America allowed many plants and animals to move between these continents, and the Nearctic ecozone shares many plants and animals with the PalearcticThe Palearctic or Palaearctic is one of the eight ecozones dividing the Earth surface (see ). Physically, the Palearctic is the largest ecozone. It includes the terrestrial ecoregions of Europe, Asia north of the Himalaya foothills, northern Africa, and t. The two ecozones are sometimes included in a single Holarctic ecozone.
Many large animals, or megafaunaThe large animals of any particular area or time are its megafauna . Generally a "large animal" is considered to be one weighing over 100 pounds (45 kg). Aside from its general and more strictly correct meaning, the term is often used as a shorthand way o, including horseThis article discusses ungulate mammals. For other meanings of horse see Horse (disambiguation). The Horse Equus caballus is a large ungulate mammal, one of the seven modern species of the genus Equus''. It has long played an important role in transportats, camelCamelus bactrianus Camelus dromedarius A camel is either of the two species of large even-toed ungulate in the genus Camelus the Dromedary (Single hump) and the Bactrian Camel (Double hump). Both are native to the dry and desert areas of Asia and northerns, mammothA mammoth is any of a number of an extinct genus of elephant, often with long curved tusks and, in northern species, a covering of long hair. They inhabited the northern regions of the world, in Europe, northern Asia, and North America. Many types of mamms, mastodonts, ground sloths, sabre-tooth cats ( Smilodon), the Giant Short-Faced Bear (Arctodus simius), and the cheetah, became extinct in North America at the end of the Pleistocene epoch (ice ages), at the same time the first evidence of humans appeared, in what is called the Holocene extinction event. Previously it was believed that the megafaunal extinctions were caused by the changing climate, but many scientists now believe that while the climate change contributed to these extinctions, the primary cause was hunting by newly-arrived humans or, in the case of some large predators, extinction resulting from prey becoming scarce. The American Bison (Bison bison), Brown Bear or Grizzly Bear (Ursus arctos), and Wapiti or Red Deer (Cervus elaphus) entered North America around the same time as the first humans, and expanded rapidly, filling ecological niches left empty by the newly-extinct North American megafauna.
One bird family, the wrentits (Timaliinae), is endemic to the Nearctic region. The Holarctic has four endemic families: divers (Gaviidae), grouse (Tetraoninae), auks (Alcidae), and the waxwings (Bombycillidae).
Animals originally unique to the Nearctic include:
Plants originally unique to the Nearctic include families: