Dicynodonts were therapsids, mammal-like reptiles that evolved in mid Permian time and continued through the Triassic. They were herbivorous with two tusks, hence the name meaning “two dog tooth”. They were also the most successful and diverse of the non-mammalian therapsids with more than 70 known genera, ranging in size from a rat to an ox. The mouth is equipped with a horny beak as in turtles. Food was processed by the retraction of the lower jaw, producing a powerful shearing action that enabled the animal to process tough plant material. The animal underwent a sharp decline in kinds and numbers during the Late Triassic, probably due to increasing aridity. With their demise, there ecological niche was overtaken by sauropod dinosaurs. With their extinction, there were no more dominant large mammal-like reptiles until the Middle Paleocene when mammalian descendants of cynodonts, began to diversify after the extinction of the dinosaurs.