The Great American Biotic Interchange was the large-scale migration of land animals and plants between North and South America after the Isthmus of Panama formed, joining two continents that had long been separate. South America had been isolated for tens of millions of years and had evolved a unique fauna, including giant ground sloths, glyptodonts and flightless terror birds. Cats, dogs, bears, horses, camels, deer and mastodons moved south, while armadillos, opossums, porcupines and some ground sloths moved north. Many South American mammals later disappeared, and scientists debate how much competition from northern arrivals and how much climate change and human hunting were responsible. The new land bridge also changed ocean circulation, with effects on global climate.
Before and after
- about 33.9 million years agoEocene–Oligocene extinction event
- about 7 million years agoSahelanthropus, one of the earliest hominins
- from about 3.3 million years ago to 15,000 years agoPaleolithic
- from about 3.3 million years ago to 302,000 years agoLower Paleolithic
- about 2.7 million years agoGreat American Interchange
- about 2.6 million years agoOldowan
- from about 1.76 million years ago to 150,000 years agoAcheulean
- from about 315,000 years ago to 33,000 years agoMousterian
- from about 302,000 years ago to 32,000 years agoMiddle Paleolithic
More in Evolution & life
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- from 1200 to 1523Aztec
- 24 November 1974Discovery of Lucy
The era
This moment belongs to the Cenozoic (66 million years ago to 300,000 years ago), the rise of mammals and the ice ages.