ANT333 Lecture #8 – Dietary Adaptations: Dentition I
Hardest biological structure in body: varying from 5-8 on Mohs scale (talc =1, diamond = 10).
Attains full thickness before teeth emerge into oral cavity.
Composed of inorganic calcium phosphate.
Thicker over cusps of unworn premolars and molars, thinner around cervical region.
Deciduous teeth have thinner enamel than permanent teeth.
Basic histological structure in mammals is calcified rods or prisms.
Not as mineralized as enamel, so softer than enamel but harder than bone.
Makes up most of tooth and root.
Composed of collagen and hydroxyhapitite.
More compressible and elastic than enamel – absorbs force placed on tooth
Does not contain variable histological patterns; thus, not of taxanomic utility for scientists.
Teeth that are regionally differentiated in form so as to serve special functions.
Four Kinds of Teeth:
Blade-like teeth that cut and shear food at the front of mouth.
Upper incisors are limited to the premaxilla bone.
Incisors are relatively small, simple teeth in most primates.
Some primate lineages have enlarged (plesiadapiformes) and/or specialized incisors, such as the
tooth combs of lemurs.
Large teeth at corners of mouth, distal to incisors, that can pierce food and whose relative size
important to social structure of many groups of primates.
Upper canine is first tooth immediately behind suture between premaxilla and maxilla.
Lower canine is tooth immediately in front of upper canine when upper and lower jaws
occluded (brought together).
Intermediate in form between canines and molars; commonly have two cusps (raised points on
the crown) so referred to as bicuspids.
Often thickened ring of enamel around base of crown called the cingulum.
In some primates, particularly OW Monkeys, anterior premolar acts as honing (sharpening)
stone to sharpen posterior edge of the upper canine when two teeth come into contact
Have expanded occlusal surface, with more cusps than premolars, for crushing and grinding
Upper molars of primates all derive from a tritubercular (triangular-cusp) pattern.
Crown of each tritubercular tooth has three main cusps 1). Protocone, 2). Metacone and 3).
1 Basic Dental Structure
Trigon – set of three major cusps – increases surface area
Earliest therian mammals had upper teeth with 3 cusps arranged in triangle, with base running
along labial edge of tooth.
In upper jaw, cusp at apex of triangle (on lingual side) termed protocone; anterior cusp along
labial margin is paracone; and posterior cusp along same margin is metacone.
Basic Dental Structure
Teeth had substantial stylar shelf (labial to paracone and metacone), which contained several
smaller cusps (styles). Set of 3 major cusps is called trigon.
Lower teeth contain a trigon (called trigonid), but triangle of cusps is turned around.
Protoconid is labial whereas paraconid and metaconid on lingual side.
Low shelf, called talonid or talonid basin, develops at posterior end of tooth.
Talonid basin ringed by three cusps: labial hypoconid, lingual entoconid, and between them, the
Evolution of Tooth Structure
The teeth of living placentals believed to evolved from tribosphenic teeth.
In tribosphenic teeth of upper jaw, three main cusps are protocone, paracone, and metacone.
Ridge called a cingulum connects main cusps.
Small shelf named stylar shelf runs along labial (lip) side of tooth. On it are located several
smaller cusps (parastyle and others).
Evolution of Quadritubercular Dentition
Early in mammalian history addition of 4th main cusp, hypocone, to upper molar.