Our understanding of evolutionary processes has changed tremendously in the last few decades, most notably by advances in genetics and developmental biology that have transformed the approaches of evolutionary biologists (Amundson, 2005; Klingenberg, 2010). Among other changes, the use of model systems has become more widespread in evolutionary biology. One of those models is the mandible of the house mouse, which is now widely used as a model for complex morphological structures in general (Atchley and Hall, 1991; Atchley, 1993).