An illustration of Pappochelys, based on its 240-million-year-old fossilized remains. This ancestor to today's turtle was about 8 inches long. Rainer Schoch/Nature hide caption

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The skull of a Giganotosaurus. Courtesy Don Lessem hide caption

toggle caption Courtesy Don Lessem

Artistic life reconstruction of the new horned dinosaur Regaliceratops peterhewsi in the palaeoenvironment of the Late Cretaceous ofAlberta, Canada. Julius T. Csotonyi/Courtesy of Royal Tyrrell Museum, Drumheller, Alberta hide caption

toggle caption Julius T. Csotonyi/Courtesy of Royal Tyrrell Museum, Drumheller, Alberta

The skull of a chicken embryo (left) has a recognizable beak. But when scientists block the expression of two particular genes, the embryo develops a rounded "snout" (center) that looks something like an alligator's skull (right). Bhart-Anjan S. Bhullar hide caption

toggle caption Bhart-Anjan S. Bhullar

The Two-Way

How Bird Beaks Got Their Start As Dinosaur Snouts

Hoping to help trace the history of how velociraptors evolved into birds, researchers at Harvard and Yale may have tracked a key beak transformation to two genes.

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An artist's rendering of what Dearcmhara shawcrossi probably looked like in dinosaur times. Todd Marshall/University of Edinburgh hide caption

toggle caption Todd Marshall/University of Edinburgh

The Smithsonian's Jon Blundell scans the fossilized foot bone — the metatarsal — of the Wankel T. rex to help create a digital 3-D image of the long-dead dinosaur. Nikki Kahn/The Washington Post hide caption

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Reconstruction of Deinocheirus mirificus. Yuong-Nam Lee/Korea Institute of Geoscience and Mineral Resources hide caption

toggle caption Yuong-Nam Lee/Korea Institute of Geoscience and Mineral Resources

Workers at the National Geographic Museum in Washington grind the rough edges off a life-size replica of a spinosaurus skeleton. Mike Hettwer/National Geographic hide caption

toggle caption Mike Hettwer/National Geographic

An artist's image of Nasutoceratops titusi. Lukas Panzarin for the Natural History Museum of Utah hide caption

toggle caption Lukas Panzarin for the Natural History Museum of Utah