Whales started small
By Sid Perkins
The ancestors of whales, some of which are the largest creatures ever to evolve, were probably mammals no larger than a fox. New fossils of Indohyus, a genus previously known only from some teeth and a jawbone fragment, led researchers to identify these deerlike creatures as the closest known relatives of primitive whales.
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Certain features of the animals’ skulls and earbones match those of whales and their close relatives but no other mammals, says Hans Thewissen, a paleontologist at the Northeastern Ohio Universities College of Medicine in Rootstown. Indohyus’ bones are thicker than average for an animal its size, a buoyancy-stifling characteristic that would have enabled it to live partly underwater. Indohyus lived about 48 million years ago in southern Asia, Thewissen and his colleagues report in the Dec. 20/27 Nature.