Evolution of the Class 1 Lever Model.

<p>The Class 1 Lever Model and mandibular bite share the same fulcrum (the temporomandibular joint) and point of resistance (the canine tips or more posterior teeth) but differ in the position and orientation of the force. The Class 1 Lever Model may have evolved when cats began to use their mandibles to bulldog prey (and thereby restrain it) and then used their forelimbs to augment the bite. The greatly increased mechanical advantage of the Class 1 Lever Model compared to the mandibular bite is visually apparent in the much greater length of its in-lever (). In the above diagram, the mandibular bite has been modeled as a Class 3 lever. Because the cranium and mandible in the mandibular bite move towards one another, the mandibular bite can also be illustrated with the force directed dorsally at the coronoid process and the resistance directed ventrally at the mandibular canine tips. C1LM, Class 1 Lever Model; MB, mandibular bite.