The dicynodont skull is highly specialised, light but strong, with the synapsid temporal openings at the rear of the skull greatly enlarged to accommodate larger jaw muscles. The front of the skull and the lower jaw are generally narrow and, in all but a number of primitive forms, toothless. Instead, the front of the mouth is equipped with a horny beak, as in turtles and many ceratopsian dinosaurs. Food was processed through retraction of the lower jaw when the mouth closed, producing a powerful shearing action (Crompton and Hotton 1967), which would have enabled dicynodonts to cope with tough plant material. Many genera also have a pair of tusks, which it is thought may have been an example of sexual dimorphism (Colbert 1969 p. 137)
The body is short, strong and barrel-shaped, with strong limbs. In large genera (such as Dinodontosaurus) the hindlimbs were held erect, but the forelimbs bent at the elbow. Both the pectoral girdle and the ilium are large and strong. The tail is short. They were cousins of the cynodonts, but unlike them they didn't have any mammalian characteristics both physical and mental (i.e. they did not care for their young like the cynodonts did). They were characterized by bony beaks and tusks protruding from the upper jaws.
In Walking with... SeriesEditDiictodon was one of the last Permian dicynodonts, and as such it exhibited several relatively advanced characteristics, such as the primitive inner-ear structure, as featured in Walking with Monsters ep. 3. It formed pairs that lived in burrows located closely to the burrows of other Diictodon, but each pair lived separately from its neighbors (unlike the modern burrow-living animals such as the rodents), not forming interconnecting colonies. The Diictodon burrows were more than a match both to predators of its time (such as the gorgonopsids) and such natural disasters such as the sandstorms, but fossils were found of Dictodon that drowned in their burrows; these small mammal-like reptiles became extinct by the end of the Permian, 252 MYA.
Lystrosaurus was a later species of dicynodonts (248-5 MYA), and at 2 meters in length, it was the size of a small pig, though it was proportionally thinner and longer. It was featured in Walking with Monsters ep. 3, as one of the smaller Diictodon's descendants (Diictodon was no bigger than 45 cm. in length), and it lived in herds and did annual migrations. That episode also showed lystrosaurs getting killed by carnivorous therocephalians and Proterosuchus, but managing to shrug off this attack by their numbers alone.
At 3.5 meters in length, ox-like Placerias was the last of the dicynodonts to have ever existed. Featured in Walking with Dinosaurs ep. 1, these animals were featured living in herds (for which the males fought dominant battles) at the end of the Triassic time period; initially they fared well enough, but eventually both the increasing droughts and the pressure from such herbivorous dinosaurs such as the Plateosaurus caused the Placerias to die out like the rest of its kind.