Also found in: Dictionary, Thesaurus.
a suborder (or superfamily) of fossilized beastlike reptiles. They were widespread at the end of the Permian and the beginning of the Triassic periods. Their size ranged from that of a rat to that of a rhinoceros. The skull was massive, the teeth atrophied except for two tusks or fangs; the jaws had the form of a beak, as in turtles. Probably they were herbivorous. Remains of Dicynodontia have been found on all continents except Australia; they are especially numerous in Upper Permian deposits of South Africa.