Central American Seaway

The Central American Seaway, also called the Panamanic Seaway or Inter-American Seaway was an ancient body of water that once separated North America from South America. It formed in the Mesozoic (200-154 mya) during the separation of the Pangaean supercontinent, and closed when the Panamanian isthmus was formed by volcanic activity in the late Pliocene (2.76-2.54 mya).

The closure of the Central American Seaway had tremendous effects on oceanic circulation and the biogeography of the adjacent seas, isolating many species and triggering speciation and diversification of tropical and sub-tropical marine fauna. It had an even larger impact on terrestrial life. The seaway had isolated South America for much of the Cenozoic, allowing the evolution of a wholly unique diverse mammalian fauna there; when it closed, a faunal exchange with North America ensued, leading to the extinction of many of the native South American forms.