“THE GREAT DYING”
THE PERMIAN EXTINCTION
250 million years ago
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| Late Permian animals around a waterhole in Russia. After the cataclysmic extinction event (the “Great Dying”) at the end of the Permian 251 million years ago, 70% of terrestrial vertebrate species and 96% of marine species went extinct (over 90% of overall species). Credit: Illustration by John Sibbick, courtesy of John Sibbick Illustration. This illustration is used with permission. All rights reserved. |
Catastrophic environmental changes due to one of the largest volcanic episodes in our planet’s history 250 million years ago led to the extinction of over 90 percent of the earth’s life forms. This catastrophe also set the stage for the emergence of the dinosaurs and the earliest mammals, including our ancestors.
Imagine volcanic eruptions covering all of North America to an astonishing thickness of 1,000 feet of lava (over three football field lengths thick). This is exactly what happened in Siberia 250 million years ago, creating the so-called “Siberian Traps”, comprised of 3 million cubic kilometers of basalt lava. During this time, the supercontinent of Pangaea was created as crustal plates came together, and subsequent began to break up into the separate continents.
Here is a possible recipe for such a mega-extinction:
1. Create massive volcanic basalt lava flows in Siberia over thousands of years.
2. Emit massive amounts of sulphur dioxide and carbon dioxide from these lava flows into the atmosphere, creating a nasty “greenhouse” global warming;
3. Produce global warming, combined with acid rain, killing off most of the land plants (except for mushrooms and other fungi that do not depend on photosynthesis), causing worldwide animal starvation;
4. Increase the amount of toxic gases and decrease in oxygen leads to the asphyxiation of many land animals;
5. Wash massive amounts of decaying vegetation into the oceans, plus high levels of carbon dioxide are absorbed from the atmosphere, poison the seas, killing its plankton, and thus the food chain for aquatic life forms;
6. Deplete the seas of their oxygen (called anoxia), and the decaying sea floors emit huge quantities of poisonous hydrogen sulfide and methane;
7. Cause the extinction of over 90 percent of aquatic species and over 70 percent of terrestrial species.
One group of terrestrial reptiles that survived was the cynodont therapsid reptiles, some of which were ancestral to the warm-blooded mammals, including us.
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| A reconstruction of what Earth would have looked like during the Permian-Triassic extinction event. By Permian times, the continental landmasses had merged together through plate tectonics to form a supercontinent, Pangaea, surrounded by a super-ocean, Panthalassa. Pangaea was the latest of a series of supercontinents that have formed and then broken apart during the course of earth’s history. Credit: Image by Dr. Ron Blakey – https://jan.ucc.nau.edu/~rcb7/ Wikipedia. |
HOW DO WE KNOW?
The fossil record clearly records a major extinction event around 250 million years ago, coinciding with the massive lava flows in Siberia. The rich, diverse aquatic and terrestrial life of the Permian is replaced with impoverished diversity in the following early Triassic.
WHY SHOULD I CARE?
This evolutionary catastrophe, the largest extinction event in the history of the earth, wiped out most of the species of life, but also created new niches for the fortunate survivors. Some of these survivors would be the ancestors of the dinosaurs, the mammals, and ourselves.
It shows how radical environmental changes can have catastrophic results.
WEB RESOURCES
This is a YouTube vido about the Permian Mass Extinction
https://www.youtube.com/watch?v=hDbz2dpebhQ
This is a National Geographic article which gives an informational look into the Permian extinction.
https://science.nationalgeographic.com/science/prehistoric-world/permian-extinction.html
A website with a concise survey of the Permian mass extinction, with many links for information on specific items of interest throughout the text.
https://park.org/Canada/Museum/extinction/permass.html
Another website with a brief outline of what might have happened in the Permian mass extinction, or the Great Dying, as it is sometimes referred.
https://dsc.discovery.com/dinosaurs/permian-extinction.html
