The anatomical term heterodont (from Greek, meaning 'different teeth') refers to animals which possess more than a single tooth morphology. For example, members of the Synapsida generally possess incisors, canines ('eyeteeth'), premolars, and molars. The presence of heterodont dentition is evidence of some degree of feeding/hunting specialization in a species. By contrast, homodont ('same teeth') dentition is the plesiomorphic (primitive) state for vertebrates, and is common in elasmobranchs, bony fish, amphibians, and most reptiles. Within the Sauropsida, there are occasionally cases of heterodonty, in some forms of pterosaurs, lizards, and dinosaurs, for example.
The term heterodont can also refer to members of the Subclass Heterodonta of the Class Bivalvia. The name refers to the differentiated hinge teeth which hold together the valves of the shell.