Chickens, Horner says, have the keys to building a dinosaur etched into their genomes. Things like teeth, claws, and tails are still expressed in embryonic chickens, but are all turned off at some point during embryonic development by genes that evolution has made ubiquitous in modern birds. By turning these genes off, we've already engineered chickens expressing teeth, and by turning off still more we might resurrect more of the dinosaur's prehistoric traits, no mosquito mining necessary.