Permian–Triassic extinction event

Extinction intensity

Permian–Triassic extinction event

The Permian–Triassic extinction event, also known as the P–Tr extinction, the P–T extinction, the End-Permian Extinction, and colloquially as the Great Dying, represents the most severe extinction event in Earth's history, occurring approximately 252 million years ago at the boundary between the Permian and Triassic geological periods. It is characterized by the extinction of roughly 90% of marine species and 70% of terrestrial vertebrate species. This event also greatly reduced the diversity and abundance of plants and insects. The causes of the Permian–Triassic extinction event are still a subject of research and debate among scientists, with hypotheses including massive volcanic eruptions, climate change, ocean anoxia, and the possible impact of an asteroid or comet.

Causes

Several theories have been proposed to explain the causes of the Permian–Triassic extinction event. The most widely supported hypotheses include:

• Volcanic Eruptions: The eruption of the Siberian Traps, a large volcanic province in what is now Siberia, is often cited as a major contributing factor. The vast quantities of lava and volcanic gases, including carbon dioxide and sulfur dioxide, released into the atmosphere would have led to significant environmental changes, including global warming, acid rain, and ocean acidification.

• Climate Change: The end of the Permian period was marked by significant climate fluctuations, including warming and cooling periods that could have disrupted ecosystems worldwide.

• Ocean Anoxia: Evidence suggests that the world's oceans became depleted of oxygen (anoxic conditions) during the Permian–Triassic boundary, leading to the extinction of many marine species.

• Asteroid Impact: Although less supported, some scientists propose that an asteroid or comet impact may have contributed to the extinction event, similar to the Cretaceous–Paleogene extinction event that led to the demise of the dinosaurs.

Effects

The Permian–Triassic extinction event had profound effects on the Earth's biosphere. The loss of biodiversity was unparalleled, with an estimated 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It took millions of years for the Earth's ecosystems to recover from this catastrophic event, and the recovery period saw the emergence of new species and groups that would dominate the Mesozoic era, including the dinosaurs.

Recovery

The recovery from the Permian–Triassic extinction event was slow and complex. The ecosystems that emerged in the Triassic period were vastly different from those that had existed before the extinction. The period saw the rise of new groups of plants, marine and terrestrial animals, including the early dinosaurs, which would go on to dominate the planet for the next 135 million years.

Legacy

The Permian–Triassic extinction event has been the subject of extensive scientific research and has significantly influenced our understanding of extinction and the resilience of life. It serves as a stark reminder of the potential for catastrophic environmental changes to cause mass extinctions.