E-Mail IMAGE: Erica Martinho, first author of the article. Manatees first split from their common ancestor after geological events isolated the South American region from the sea. The African species may have... view more Credit: Erica Martinho All three species of manatee now present on Earth share a common ancestor from which they split some 6.5 million years ago, when a huge lake in Amazonia, then linked to the Caribbean, was cut off from the sea. The African manatee Trichechus senegalensis is not as genetically close to the West Indian manatee T. manatus as was thought, and adaptation to this complex environment by the Amazonian manatee