Permian

The Permian was the sixth and last geological period of the Paleozoic era, extending from approximately 289.9 million to 251.902 million years ago. It is divided into three epochs: the Lopingian, the Guadalupian, and the Cisuralian (Figure 1). Roderick Murchison, a British geologist, named the Permian in 1841 after Permia, an ancient kingdom that existed near the modern day Urals.

• 

  Figure 1. ICS Permian timeline.

• 

  Figure 2. Earth's landmasses in the Permian.

Pangea persisted as a massive supercontinent throughout the Permian (Figure 2). There is evidence that some of the furthest inland places had desert-like environments that experienced extreme seasonal fluctuations because they lacked the temperature-moderating effects of larges bodies of water. There is also evidence for a shifting climate, with glaciations becoming less frequent. This transition is sometimes referred to as a "icehouse to greenhouse transition", where the Earth shifts from a cooler, humid climate to a warmer, more arid one. This greatly reduced the coal producing swamps that had become established in the Carboniferous, decreasing the habitats for amphibians. Reptilian species began to become more dominant but large numbers of amphibian species still existed (Figures 3 to 5). Coniferous plants very similar to the ones that exist today first appeared with the more arid climates.

• 

  Figure 3. Edaphosaurus pogonias and Platyhystrix – Early Permian, North America and Europe.

• 

  Figure 4. Dimetrodon grandis and Eryops – Early Permian, North America.

• 

  Figure 5. Ocher fauna, Estemmenosuchus uralensis and Eotitanosuchus – Middle Permian, Ural Region.

The end of the Permian period and the Paleozoic era was marked by the largest known mass extinction to date: the Permian-Triassic extinction event. This particular extinction event most heavily affected marine species, particularly aquatic invertebrates. It is estimated that over 90% of marine species died out. On land, it is estimated that approximately 70% of the terrestrial species went extinct. While the land extinctions were not as drastic as the marine losses, they did set the scene for the Mesozoic era, often referred to as the "Age of the Dinosaurs", to begin.

Figure 6. The ICS Chronostratigraphic Chart

For Further Reading

• Geologic time scale
• Geologic period
• Climate change
• Coal
• Stratigraphy
• Or explore a random page