![]() ![]() In contrast to other tetrapods, the evolution and diversity of teeth in amphibians has been poorly studied, despite long recognition that frogs-one of the most diverse vertebrate orders with more than 7000 species-possess variation in the presence or absence of teeth.Īll living salamanders and caecilians are assumed to have teeth on the upper jaw, lower jaw, and palate ( Duellman and Trueb, 1986), but nearly all frogs lack dentition on the lower jaw and variably possess teeth on the upper jaw and palate. Teeth are likely lost following the evolution of a secondary feeding tool that improves the efficiency of food intake (e.g., beak, baleen, specialized tongue), leading to relaxed functional constraints on dentition ( Davit-Béal et al., 2009). Although dentition is generally conserved across vertebrates, teeth have been lost completely several times, resulting in toothlessness or edentulism, including in three extant clades of mammals (baleen whales, anteaters, and pangolins), turtles, and birds ( Davit-Béal et al., 2009). ![]() The shape, size, location, and number of teeth differ widely across vertebrates, especially in response to broad variation in food type. Teeth are complex mineralized tissues that originated in stem gnathostomes more than 400 million years ago ( Rücklin et al., 2012) and have been broadly maintained across living chondrichthyans, actinopterygians, and sarcopterygians due to the critical role these structures play in the acquisition and processing of food. The evolution of teeth is considered a key innovation that promoted the radiation of jawed vertebrates, facilitating the transition from a passive to active predatory lifestyle ( Gans and Northcutt, 1983). ![]()
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