Modern dolphins (below) and extinct marine reptiles called ichthyosaurs (above) descended from distinct terrestrial species, but independently converged on an extremely similar fish-like body plan although they were separated in time by more than 50 million years. In April 2015, a team of
Smithsonian scientists synthesized decades of scientific discoveries to illuminate the common and unique patterns driving the extraordinary transitions that whales, dolphins, seals and other species underwent as they moved from land to sea, offering a comprehensive look at how life in the ocean has responded to environmental change from the Triassic to the Anthropocene.
(Dolphin image courtesy of NOAA. Ichthyosaur image courtesy of Lindgren et. al, Nature Publishing Group)