Examples showing the bifurcated mandibular fat body (indicated by red dots) attached to the TPC.

Each panel shows a transverse section, from CT scans, through the TPC (white), and both branches of the mandibular fat body (dark gray marked with red dots). Note that the lower branch of the MFB (lower red dot in each subpanel) attaches on the tympanic bulla. The upper branch of the MFB (upper red dot in each subpanel) fits into the funnel or notch between the tympanic and periotic bones. These examples span all major groups of odontocetes except sperm whales (Physeteroidae) and the eclectic “river dolphins” (Pontoporiidae + Platanistoidae). The panels are not scaled equally.