The continents of North and South America came together much earlier than previously thought , according to researchers who found evidence in rock deposits from ancient rivers in Colombia of the land bridge that connected the long-isolated landmasses . The two continents are linked at Panama , but there has been a debate about when this land bridge first appeared , with most experts placing its formation at about 3 million years ago . The new study , published on Thursday in the journal Science , presents evidence that the Panama land bridge formed at least 10 million years earlier . Before the Isthmus of Panama rose from the sea by tectonic and volcanic action , the Central American Seaway linked the Atlantic to the Pacific as one great ocean . The various continents , sitting atop huge plates akin to jigsaw puzzle pieces sliding over Earth 's mantle , have slowly moved around the globe during the planet 's history . They have separated , drifted and joined numerous times in a process called plate tectonics . South America became an isolated landmass when it separated from Africa . Likewise , North America broke apart from Europe and headed on a gradual collision course with South America . Until then , a deep water channel called the Central American Seaway separated the continents . The researchers base their estimate on the presence of small grains of a mineral called zircon unearthed in ancient river bedrock in northern Colombia that originated in Panama and were 13 million to 15 million years old . These grains suggested the land bridge must have existed at that time , they said . 'We contend that a bridge , perhaps a transient one , was present since 13 to 15 million years ago , ' said geologist Camilo Montes of Universidad de los Andes in Bogota , who led the study . 'Beds younger than about 13 to 15 million years contain abundant zircon grains with a typically Panamanian age , ' said Montes . 'Older beds do not . 'We think these zircons were deposited by rivers flowing from the Isthmus of Panama when it docked to South America , nearly 10 million years earlier than the date of 3 million years that is usually given for the connection . ' The various continents , sitting atop huge plates akin to jigsaw puzzle pieces sliding over Earth 's mantle , have slowly moved around the globe during the planet 's history . They have separated , drifted and joined numerous times in a process called plate tectonics . South America became an isolated landmass when it separated from Africa . Likewise , North America broke apart from Europe and headed on a gradual collision course with South America . One of the most dramatic results of the joining of the two Americas was the mixing of the animals living on the respective landmasses , with various creatures crossing the land bridge to invade the other continent . The event is known as the Great American Biological Interchange . After the Isthmus of Panama formed , animals and plants could move back and forth between continents , the Great American Biological Interchange . Smithsonian scientists are debating when this happened . South America had a unique animal population , with exotic marsupials including saber-toothed predators , as well as elephant-sized ground sloths , car-sized armadillos , camel-like creatures with elephant trunks and giant flightless , carnivorous 'terror birds . ' North America had a quite different and impressive array of placental mammals including saber-toothed cats and other feline predators , huge short-faced bears , wolves and various herbivores including big elephant relatives and horses . The two continents continue to move together . 'Yes , the plates are moving today , ' Montes said . 'They never stop . ' Sorry we are not currently accepting comments on this article .
Researchers had previously believed continents connected 3m years ago . Deep water channel called Central American Seaway separated continents .