Lystrosaurus is an extinct genus of dicynodont therapsid that lived during the Late Permian and Early Triassic periods, around 250 million years ago in what is now Antarctica, India and South Africa. At present 4 to 6 species are recognized, although from the 1930s to 1970s the number of species was thought to be much higher. Lystrosaurus had only two teeth, as with all other dicynodonts, as well as a pair of tusk-like canines. Lystrosaurus is thought to have had a horny beak that was used for biting off pieces of vegetation. Lystrosaurus was a heavily-built, herbivorous animal, approximately the size of a pig. The structure of its shoulders and hip joints suggest that Lystrosaurus moved with a semi-sprawling gait. Lystrosaurus was by far the most common terrestrial vertebrate of the Early