What is the Great American Interchange?
The Great American Interchange may sound like some sort of freeway, but it’s actually a paleozoogeographic event that occurred in the Americas about 3 million years ago, during the Pliocene epoch. The Great American Interchange was caused when volcanic activity created the Isthmus of Panama, linking together North and South America, which had been separated for 200 million years, since the breakup of the supercontinent Pangaea. Numerous mammals, part of lineages which had been separated for eons, were exchanged between the continents, which thereafter became part of the same general biogeographical region, the Americas. The mammalian fauna of North America prior to the Great American Interchange were in general boreoeutherian, a clade composed of sister taxa Laurasiatheria and Euarchontoglires, which encompasses the New World primates, lagomorphs (pikas, rabbits, hares), rodents (rats and mice), moles, shrews, gophers, ancient horses, deer, the now-extinct American Camel, skunks, bears
