Fig. 2. Graph illustrating the mass of the external adductor for a given cranial length in lizards from three different families (agamids, scincids and geckos; closed circles) and Sphenodon punctatus (open circles). Note how S. punctatus has a significantly smaller jaw adductor for its cranial length than the lizards examined. Data include both masses from Gorniak et al. (Gorniak et al., 1982) and newly obtained data by dissection of an adult male specimen.