Creatures that lived in the Permian period. The geologic period and system which extends from 298.9 to 252.2 million years ago. It is the last period of the Paleozoic Era, following the Carboniferous Period and preceding the Triassic Period of the Mesozoic Era. The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs and archosaurs. The world at the time was dominated by a single supercontinent known as Pangaea, surrounded by a global ocean called Panthalassa.