Evolution of Paraoral Labial Tooth Rows in Anuran Larvae

In the tadpoles of some anuran species, there is a set of one or more anterior labial tooth rows that are divided by the upper jaw sheath, which we call paraoral tooth rows. We studied the taxonomic distribution of these tooth rows based on published information and preserved specimens in 4,595 species of anurans from all currently recognized families. Paraoral rows were recorded in 594 species, most belonging to Ranoides and Anomocoela, but also occurring in Myobatrachoidea and a few notogaeanurans. The reconstruction of ancestral states indicated at least 15 independent origins of the character state during the evolutionary history of the anurans. The paraoral rows are a typical character of Anomocoela and Ranoides. The presence of paraoral rows was retained in both clades during their evolutionary history when specialized morphologies evolved, as long as labial teeth were not lost.