Connection between North and South America was relatively recent: Study

PANAMA CITY, Panama, Aug. 18 (UPI) -- Some scientists have suggested the Isthmus of Panama bridged the divide between North and South America several million years prior to the current consensus of 3 million years ago. But a new survey reaffirms the relatively recent connection of the two continents.

The confirmation has quelled concerns among scientists that many theories and models needed rethinking and recalibration.

"Recent scientific publications proposing the isolation of the two oceans between 23 to 6 million years ago rocked the generally held model of the continental connection to its foundations," Jeremy Jackson, emeritus staff scientist at the Smithsonian, explained in a news release. "O'Dea and his team set out to reevaluate in unprecedented, rigorous detail, all of the available lines of evidence -- geologic, oceanographic, genetic and ecological data and the analyses that bear on the question of when the Isthmus formed."

Aaron O'Dea, staff scientist at the Smithsonian Tropical Research Institute, is the lead author of the new paper, which posits the Isthmus of Panama dissected the Atlantic and Pacific oceans beginning around 2.8 million years ago.

O'Dea and an international team of scientists, including researchers from 23 institutions, re-examined all the evidence pertaining to the isthmus' formation. Scientists looked at marine and terrestrial fossils, as well as volcanic and marine rocks. They also traced the genes of animals that shared an evolutionary history prior to the presence of the land bridge.

All of the evidence points same conclusion: North America and South America forged a geologic bond some 3 million years ago. It's around that time that marine mammals on either side stopped sharing genes, and when land mammals began mass migrations between the two continents.

"Our review and new analyses aims to clarify the issue by bringing together expertise from a wide array of different lines of evidence," researchers wrote in their paper, newly published in the journal Science Advances. "Given all the available evidence, we strongly caution against the uncritical acceptance of the old isthmus hypothesis."