Anomodontia is an extinct group of non-mammalian therapsids containing many species from the Permian and Triassic periods (possibly continuing into the Early Cretaceous), most of which were toothless herbivores. Anomodonts were very diverse during the Middle Permian, including primitive forms like Anomocephalus and Patranomodon and groups like the Venyukovioidea, the Dromasauria, and the Dicynodontia. Of these only the dicynodonts survived beyond the Middle Permian. Dicynodonts became the most successful and abundant of all herbivores in the Late Permian and Triassic, filling ecological niches ranging from large browsers down to small burrowers. Few dicynodont families survived the Permian–Triassic extinction event, but one lineage evolved into large, stocky forms that remained the dominant terrestrial herbivores right up until the Late Triassic, when changing conditions caused them to decline.