 Cingula are often incomplete ridges that pass around the base of the crown.Mammalian, multicusped cheek teeth probably evolved from single-cusped teeth in reptilians, although the diversity of therapsid molar patterns and the complexity in the molars of the earliest mammals make determining how this happened impossible.According to the widely accepted "differentiation theory", additional cusps have arisen by budding or outgrowth from the crown, while the rivalling "concrescence theory" instead proposes that complex teeth evolved by the clustering of originally separate conical teeth.