Everett Olson and His Contribution to the Mass Extinction Narrative.

Greetings. Olson's Extinction, named after paleontologist Everett C. Olson, was a mass extinction that occurred approximately 273 million years ago during the Late Permian period. The extinction predated the monumental Permian/Triassic extinction event by a few million years. 

Olson first identified a substantial gap in fossil record strongly indicating an abrupt change between the early Permian and middle/late Permian faunas. This event has been argued by many paleontologists to have affected many taxa, including embryophytes, marine metazoans, and tetrapods.

The first signs that indicated extinction came to light when Olson noted a hiatus between early Permian faunas dominated by pelycosaurs and the therapsid-dominated faunas of the middle and late Permian. Initially taken to be a preservational gap in the fossil record, the event was originally dubbed "Olson's Gap." To compound the difficulty in identifying the cause of the "gap," paleontologists had difficulty in resolving the uncertainty which exists regarding the duration of the overall extinction and about the timing and duration of various groups' extinctions within the greater overall process. Theories were offered that suggested the extinction was prolonged, spread out over several million years or that multiple extinction pulses preceded the Permian/Triassic extinction event. One thing is known beyond a shadow of a doubt; Olson's Extinction amplified the effects of the soon to come Permian/Triassic extinction event with the final extinction counts reaching almost 95% of all species of complex life on the planet, regardless of environment. 

Extinction rates in fish increased noticeably around the time of Olson's extinction. However, origination rates also rose, and so there does not appear to have been any substantial decrease in species diversity or overall numbers. 

Plants displayed a large turnover in the mid-to-late Permian and into the subsequent Triassic. The length of time that showed higher extinction rates in land plants was about 23.4 million years, starting from Olson's Extinction and into the Middle Triassic. Olson's Extinction represents the third highest peak of extinction rates seen in plants throughout the Paleozoic, and the total number of genera fell by roughly 25%. Seed plants seem to have been largely unaffected, whilst free-sporing plants were heavily affected. 

Dimetrodon, the genus of synapsid tetrapods that lived during the middle to late Permian, went extinct during Olson's Extinction. All dozen species disappeared, never to return. 

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