Teeth have clearly evolved a number of times, and one of the more interesting curiosities is found in the amphibians, notably in the frogs where several groups have independently evolved fangs.

Teeth are a rich source of insight into evolutionary convergence, amongst which some of the most spectacular are amongst the mammals, notably the sabre-tooth cats and thylacosmilids. Teeth have clearly evolved a number of times, and one of the more interesting curiosities is found in the amphibians, notably in the frogs where several groups have independently evolved fangs. The major fanged frog genus, Limnonectes, comprises around 53 species (e.g. the Fanged river frog Limnonectes macrodon) originating from South East Asia and the Phillipines. 

The specific case of frog fangs is a nice example of evolution in at least two ways. First, it is clear that the ontogenetic pathways are different from those by which fangs are formed in other vertebrates (e.g. snakes), with the possible implication that so too are the developmental pathways. This, of course, touches on one of the central questions in evolutionary convergence, that is how different can the pathways be to the same solution? Second, the selective pressure that results in the evolution of frog fangs may result from either natural selection or sexual selection. If natural selection, then it is dietary in as much as frogs with fangs are able to tackle bigger prey. If it is sexual, then not surprisingly the species are dimorphic, males with the impressive fangs. Interestingly, one species of frog combines sexual and natural selection, in as much as the males engage in combat and also have a specialized diet of relatively large prey.