A functional interpretation of the varanid dentition (Reptilia, Lacertilia, Varanidae)

A cinéradiographic analysis of the feeding movements in Varanus bengalensis produced the following results. The mouth is opened by raising the head (upper jaw) rather than by lowering the lower jaw. Starting from the resting position, the muzzle unit is elevated around 9 degrees relative to the rest of the skull during jaw opening; the quadrate swings anteriorly around 21 degrees. During jaw closure, the snout is depressed around 15 degrees relative to the rest of the skull, hence 6 degrees beyond the resting position. The quadrate swings backwards around 27 degrees. Amphikinesis is interpreted as allowing a stronger posterior recurvature of the maxillary teeth in Varanus. This increases the holding effect of the teeth without increasing their length, an adaptation of Varanus to capture relatively large prey. The formation of plicidentine (dentine infolding) in the teeth of Varanus increases the surface of attachment of the teeth on the supporting bone. Moreover, the dentine lamellae take up tensile and compressive stresses along their long axes upon axial or vertical loading of the teeth. The slope of pleurodonty is modelled so as to minimalize shear stress on the surface of ankylosis upon axial or vertical loading of the teeth.