Permian: 299–251 million years ago

Deserts and ice shape life and landscapes

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Illustration of Dimetrodon and Edaphosaurus.
Image: John Sibbick
Source: John Sibbick

280 million years ago.
Image: Ron Blakey. Altered by Cally Bennet and Fons VandenBerg
Source: Colorado Plateau Geosystems

Permian

During the Permian, the landmasses merged, forming a ‘supercontinent’ called Pangea. The remainder of the Earth’s surface comprised a single ocean. Polar ice caps covered the southern (Gondwanan) part of Pangea, while desert areas covered the northern inland part of the continent.

Land animals such as amphibious tetrapods and reptiles lived in the zones where plant life thrived. The oceans teemed with fish and invertebrates until the end of the Permian, when the biggest natural disaster in history killed 90 per cent of the planet’s species. The cause is not yet known – perhaps an asteroid impact, stagnant oceans, massive volcanic eruptions, a significant fall in sea levels, or a combination of these. Many marine groups became extinct including tabulate and rugose corals, eurypterids and the trilobites.

The ‘great dying’ also had an impact on life on land. The extinction of many plants reduced the food supply for large plant-eating reptiles and removed habitat for insects. The ancestors of mammals, dinosaurs and the reptiles we see today survived in small numbers.

Australia lay beneath an ice cap at the start of the Permian and Victoria was swathed in a slow-moving ice-sheet. As the ice retreated, forests developed with Glossopteris (seed ferns), tree-ferns, club-mosses and horsetails. As the climate became drier, plants such as conifers, cycads and ginkgos evolved. Amphibious tetrapods, reptiles and a great variety of insects inhabited these forests.