Trituberculy

Trituberculy \Tri`tu*ber"cu*ly\, n. [Pref. tri- + L. tuberculum
   tubercle.] (Zool.)
   A theory of the development of mammalian molar teeth. The
   primitive stage is that of simple cones, as in reptiles. The
   simple cone then developed a smaller cone in front and
   another behind. Next, a cingulum was developed, and the three
   cones became arranged in a triangle, the two smaller cusps
   having moved to the outer side in upper and to the inner in
   lower molars. This primitive triangle is called the trigon or
   trigonid and this stage the tritubercular or trigonodont. The
   trigon being a cutting apparatus, an extension of the
   posterior part of the crown was developed in lower molars for
   crushing, and a smaller corresponding part appeared in upper
   molars. Another large cone then arose, usually from the
   cingulum. In more complex forms, smaller intermediate cusps
   appeared.
   [Webster 1913 Suppl.]