Chickens do not have teeth, but studies have shown that chickens have the genes required to grow teeth. Evolution is likely to be the cause behind chicken's inability to activate tooth development during growth.
In 2006, biologist John Fallon from the University of Wisconsin discovered tooth growth in chicken embryos. The teeth that grow resemble baby alligator teeth, showing genetic similarities to their reptilian ancestors, the archosaurs. Fallon worked with the talpid 2 mutation strain, which forms teeth in the embryonic stage. However, whether the teeth continue to develop is unknown, as the embryos die before reaching the growth stage required to hatch..