[1] Viewed from the side, these teeth have a series of triangular cusps or ridges, enabling the ruminants' sideways jaw motions to break down tough vegetable matter.
[3] Apart from helping grind the food to properly reduce the size of substrates for stomach enzymes, their minor role is in giving shape and definition to the animals' jaws.
The shape of cheek teeth are directly related to their function, and morphological differences between species can be attributed to their dietary variations.
Additionally, the shape a cheek tooth can be mechanically worn down based on diet, which is used to provide insights into the consumption habits of fossilized animals.
Therian mammals (placentals and marsupials) are generally agreed to have evolved from an ancestor with tribosphenic cheek teeth, with three main cusps arranged in a triangle.