Long ago,one mighty ocean flowed between North and South America. When the narrow Isthmus of Panama joined the continents approximately 3 million years ago, it also separated the Atlantic from the Pacific Ocean. If this took place millions of years earlier, or as recently asserted by some,the implications for both land and sea life would be revolutionary. Aaron O'Dea, staff scientist at the Smithsonian Tropical Research Institute (STRI), or colleagues writing in Science Advances firmly set the date at 2.8 million years ago.
Source: phys.org