Lystrosaurus was a relatively large herbivorous Dicynodont, one of the mammal like reptiles.
Walking With Dinosaurs[]
Lystrosaurus didn't appear in the main series.
Walking With Monsters[]
A Diictodon evolves into Lystrosaurus. When Lystrosaurus migrate at night, a therocephalian called Euchambersia killed a Lystrosaurus with its deadly bite with toxic venom, which is more lethal than a black mamba's, though none of the other members are aiding the dying member. The Lystrosaurus dies and the Euchambersia clan feast. The Lystrosaurus cross a river and many were killed by gathered Proterosuchus. A Lystrosaurus later bumps into the camera screen and sniffs it. At the end, a Lystrosaurus corpse is seen as a Euparkeria feasts on the dead creature.