Yup - chickens (at least certain mutants) can grow teeth...

The researchers recently created more Talpids by tweaking the genes of normal chickens to grow teeth.

"What we discovered were teeth similar to those of crocodiles—not surprising as birds are the closest living relatives of the reptile," said Mark Ferguson of the University of Manchester.

So they're not that rare.

Interestingly, the mutation is also evidence of birds' dinosaur ancestry...