D. Mammals Marked by a loss of the sclerotic bones, and an increase in other structures associated with sense organs and change in the feeding apparatus. Epiglottis also forms to deflect food away from larynx entrance and into esophagus. Hard palate also leads to shift in dentition. Teeth located at jaw margins and socketed in the jaw itself. Primitive condition of teeth is thecodont, which is undifferentiated tooth structure.
Derived condition is heterodont, where teeth are modified for different functions.
Incisors used for nipping, canines for tearing, and premolars and molars used for grinding.