Olson's Extinction

Olson's Extinction is a hypothesised extinction event that is suggested to have occurred around 273 million years ago in the late Cisuralian or early Guadalupian epoch of the Permian period, predating the much larger Permian–Triassic extinction event. The event is named after American paleontologist Everett C. Olson, who first identified a sharp disjunction in the fossil record indicating a sudden change between the early Permian and middle/late Permian faunas which was hypothesised to represent a hiatus in the fossil record termed "Olson's Gap", though the nature, existence, and timing of the gap is contested. This event has been argued by some authors to have affected many taxa, including embryophytes, marine metazoans, and tetrapods.

The veracity of the extinction event has been disputed by a number of authors, who propose that it is an artifact of poor sampling and may conflate gradual change that occurred over a longer period of time.