The Permian ended in the Great Dying, the worst extinction on record
The Permian closed 251.9 million years ago with the largest mass extinction Earth has known. Roughly 81 percent of marine species and 70 percent of land species vanished, a collapse linked to the eruption of the Siberian Traps. Life on land needed around 30 million years to rebuild its ecosystems.
The period lasted 47 million years, beginning 298.9 million years ago, and was the last of the Paleozoic Era. Nearly all land was fused into the supercontinent Pangaea, ringed by the superocean Panthalassa. After the Carboniferous rainforests collapsed, vast deserts spread across the interior, and amniotes, animals better equipped for dry conditions, took over from their amphibian ancestors. Two great branches flourished: the synapsids, the lineage leading to mammals, and the sauropsids, or reptiles.
The Great Dying was not the only crisis. Researchers have proposed three or perhaps four extinction events in the period, some disputed. Early primitive synapsids known as pelycosaurs gave way to more advanced therapsids in a poorly understood turnover sometimes called Olson's Extinction, and the end of the Middle Permian brought the Capitanian mass extinction, tied to volcanic outpourings known as the Emeishan Traps.
Sir Roderick Murchison, president of the Geological Society of London, named the period in 1841 after exploring near the Ural Mountains with Édouard de Verneuil. He took the name from the Russian region of Perm, itself named for the medieval kingdom of Permia. German geologists had already labelled equivalent rocks Rotliegend and Zechstein, and in Britain they were the New Red Sandstone. The concept stayed contentious for a century: until 1941 the United States Geological Survey treated the Permian as merely a subdivision of the Carboniferous.
Today the period is split into three epochs, the Cisuralian, Guadalupian and Lopingian, a scheme formally proposed by Glenister and colleagues in 1999 after decades of a simpler two-part split. Its boundaries are defined by first appearances of particular conodonts, tiny jawless animals with tooth-like parts, because ammonoid fossils are too rare and long-lived to date rocks precisely. The Guadalupian takes its name from the Guadalupe Mountains of Texas and New Mexico.
Source: Permian
