Key insights from 3D periotic morphology in odontocete taxonomy.

This study investigates the morphological variation of the periotic bone—a dense ear bone housing inner ear structures critical for hearing—in 32 species of odontocetes (toothed whales) across five families (Delphinidae, Pontoporiidae, Phocoenidae, Ziphiidae, and Physeteridae) using 3D geometric morphometrics and photogrammetry. Results reveal two distinct periotic morphotypes: one shared by Ziphiidae and Physeteridae, and another grouping Delphinidae, Pontoporiidae, and Phocoenidae, reflecting both phylogenetic relationships and ecological adaptations. Phylogenetic analyses show a strong evolutionary signal in periotic shape, while ecological factors such as diet, habitat, diving behavior, and biosonar type significantly influence its morphology. The findings underscore the periotic bone’s taxonomic value for distinguishing odontocete families and highlight how auditory structures have evolved in response to ecological pressures.