The cheek teeth (molars and premolars) of mammals are often
marvelously complex and adapted to specific tasks. Their
morphology has provided a rich source of material for studying
both mammalian phylogeny and the process and pattern of
evolution. Complex structure inevitably leads morphologists to
creating complex terminology, and the sheer number of terms that
a student of dental variation may encounter is overwhelming. For
example, Philip Hershkovitz, in a monograph of a group of South
American rodents (1962, Fieldiana: Zoology, 46:1-524), created a
very useful and much-followed terminology that included over 60
names to describe variation in the surfaces of a set of six
teeth (three upper, three lower) none of which is much larger
than the head of a pin! In this section, we focus on the pattern
of cusps and other structures located mainly on the occlusal
surface of molars. Fortunately, we have a reasonably good idea
of how these patterns have evolved, and they can be traced back
to a fairly simple pattern