How Whales Lost Their Teeth, And Evolved Into The World’s Largest Filter Feeders

Source: Science/April Reese

Photo: “Mike” Michael L. Baird/Wikimedia Commons

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Blue whales and their cousins are the only creatures on Earth that catch their food using baleen, giant combs of keratin that filter millions of liters of water a day for their microscopic meals. But whales’ early ancestors had teeth, much like today’s killer whales, and scientists have struggled to explain how their feeding system evolved. Now, a rare fossil offers an answer: Ancient whales likely first lost their teeth and suctioned up their food, as salmon and some other fish do, then evolved baleen.

Other recent research had suggested the transition from teeth to baleen involved a slow, seamless transformation from one to the other. For example, one 30-million-year-old fossil whale found in Washington had picket, fencelike teeth with small gaps that could have filtered food. Another hypothesis posits that for a time, whales fed using both teeth and baleen. But analysis of a nearly complete whale skull presented here yesterday at the Society of Vertebrate Paleontology’s annual meeting contradicts both of those theories.

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Photo: “Mike” Michael L. Baird/Wikimedia Commons

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