Do Frogs Have Teeth? Yes, Then No, Then Yes Again, Apparently

Some frogs have teeth on their upper jaws and mouths, with one species having both upper and lower sets, while others are toothless. Frogs have lost and regained teeth over 20 times in their evolution, more than any other vertebrates, likely due to their diet of small invertebrates. This phenomenon of losing and regaining traits goes against evolutionary rules, such as Dollo’s Law of Irreversibility, seen in other species like limpets and lizards.

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