Frogs show unique tooth evolution with some species gaining and losing teeth multiple times

Some frogs have teeth, primarily on their upper jaws, while others are toothless. Only one species has both upper and lower teeth. Frogs have lost and regained teeth over 20 times in their evolution, more than any other vertebrates. This tooth loss and regrowth relate to their diet. Frogs that eat small invertebrates rely less on teeth for capturing prey. Some species, like the Pacman frog, have teeth-like structures that are not functional. Frog teeth evolution challenges the idea that lost traits cannot return. This phenomenon is also seen in other species, such as turtles and birds, which have similarly lost and regained traits over time.