Feb 16, 2015

When marine mammals such as whales, dolphins, manatees and walruses moved from land to water, a series of physical abilities –– limbs adapted for swimming, less dense bones that make them more buoyant and a large store of oxygen relative to their body size – made it possible. Yet these animals made the transition from land to water millions of years apart.
In a report that appears online in the journal Nature Genetics, an international consortium of researchers that includes those at Baylor College of Medicine looked at the genomes of these four marine mammals and compared them to their closest land kin.