That's right! Chickens have retained the ability to grow teeth. These means that horses might have retained the ability to grow a horn like a unicorn, and humans might have retained the ability the grow a third eye or be 10 feet tall...
Working late in the developmental biology lab one night, Matthew Harris of the University of Wisconsin noticed that the beak of a mutant chicken embryo he was examining had fallen off. Upon closer examination of the snubbed beak, he found tiny bumps and protuberances along its edge that looked like teeth--alligator teeth to be specific.
Exactly how the mutation causes the chickens to sprout teeth is unknown, Fallon notes, but a similar effect can be produced in normal chickens. Harris proved this by engineering a virus to mimic the molecular signals of the mutation and caused normal chickens to briefly develop teeth that were then reabsorbed into the beak.
