Figure 4

Figure 4

Figure 4 — The skull of the nectridean Keraterpeton galvani A) in side view, showing how the extend lower jaw would act as a lever; and B) showing the roof of the mouth, highlighting the rounded denticles. Abbreviations: d, denticle; em, extended mandible; jdm, jaw depressing mandible. Adapted from Milner (1980) and Carroll et al. (1998).