A freaky fish with a head like a dolphin and a body like a tank may be to thank for human jaws.
The discovery of a 423-million-year-old armored fish from China suggests that the jaws of all modern land vertebrates and bony fish originated in a bizarre group of animals called placoderms, researchers report in the Oct. 21 Science,
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.
Along with a different placoderm fossil from 2013, the new find,
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, named Qilinyu rostrata,
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, is helping rewrite the story of early vertebrate evolution, says paleontologist John Maisey of the American Museum of Natural History in New York City, who was not involved with the work.
“We’ve suddenly realized we had it all wrong,
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,” he says.
The jaws of humans — and dogs,
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, salmon,
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, lizards and all other bony vertebrates — contain three key bones: the maxilla and premaxilla of the upper jaw, and the dentary of the lower jaw.
“Anything from a human being to a cod has recognizably the same set of bones in the head,” says study coauthor Per Ahlberg, a paleontologist at Uppsala University in Sweden. The big question, he says, is “Where did these bony jaws come from?”
More than a hundred million years before dinosaurs walked the Earth,
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, fishes called placoderms thrived under water. Scientists knew that these armored fishes were early jawed animals, but their jaws were unusual: ?“They look like sheet metal cutters,
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,” Ahlberg says. “They’re these horrible bony blades that slice together.”

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