The term comes from the Ancient Greek roots σελήνη (selḗnē, 'moon' or 'moonlike'), and ὀδούς, ὀδόντος (odoús, odóntos, 'tooth'). They differ from human molars in that the occlusal surface is not covered in enamel; rather, the layers of enamel, dentine, and cementum are all exposed, with cementum in the middle, surrounded by a layer of enamel, then a layer of dentine, all wrapped in a second outer layer of enamel.
Viewed from the side, selenodont teeth form a series of triangular cusps. The combination of triangular profiles with ridges formed by the exposed layers makes the sideways jaw-motion of ruminants (think of a cow chewing) an effective way to break-up tough vegetable matter.
- Dorit, Robert L.; Warren F. Walker Jr; Robert D. Barnes (1991). Zoology. Orlando, Florida, USA: Saunders College Publishing. pp. 925–926.