BANBURY, B.L.*; BUCHHOLZ, K.; MAGLIA, A.M.; University of Missouri-Rolla; University of Missouri-Rolla; University of Missouri-Rolla: Morphometric analyses of cranial development in pelobatid frogs

The developmental osteology of pelobatid frogs (Anura: Pelobatidae) has been the subject of several studies. Despite this, little is known about the cause of the extreme variation in degree of adult cranial ossification within the group. Pelodytes and Spea are gracile, poorly ossified frogs, whereas Pelobates and Scaphiopus are robust and hyperossified. Because Scaphiopus and Spea are sister-taxa, this suggests that hyperossification has either evolved twice in the group, or has been lost at least once. Herein we provide baseline quantitative data on the development of the larval cranium and cranial ossification of four pelobatid species (one representing each genus). We used linear and geometric morphometric methods to analyze size-related shape change in the series. We discuss areas of regional shape transformation in the cranium among species (as identified by thin-plate spline deformation grids), and comment on the potential implications regarding cranial development and variation in degree of ossification in the group.