"They found that the reptiles and mammals had two patches of activity, one on either side of the developing nasal cavity. Birds, on the hand, had a much larger single patch spanning the front of the face. The researchers reasoned that the alligator pattern could serve as a proxy for that of dinosaurs, given that they have similar snouts and premaxillary bones. The researchers then undid a bird-specific pattern of gene expression in chicken embryos using chemicals to block the genes in the middle of the face. (For ethical reasons, they did not allow the chickens to hatch.)

The result: The treated embryos developed a more dinosaurlike face. “They basically grew a bird embryo back into something that looked more like the morphology of extinct dinosaurs,” said Timothy Rowe, a paleontologist at the University of Texas, Austin, who has previously collaborated with Abzhanov."