Chondrocranium and ossification sequence of Hyla lanciformis.

Tadpoles of Hyla lanciformis live in midwater and have a normal, beaked, anteroventral, subterminal mouth. Overall, they are generalized pond-type anuran larvae that show no specific modification for a particular habitat. The chondrocranium and ossification sequences of this hylid frog were studied, utilizing cleared and Alcian blue-alizarin red-stained tadpoles. The chondrocranium is similar to that of other unspecialized tadpoles. No larval otic process was found and a large process projecting from the otic capsule is considered homologous with the larval crista parotica described for other anurans. The pattern of cranial and postcranial ossification is reported. The sequence of cranial ossification is explained in the framework of functional changes of the skull through metamorphosis. Comparison with the available information for other hylid frogs shows clear differences in the ossification sequences. The sequence of postcranial ossification is described for the first time for any species of hylid frog.