Olson's Extinction
Olson's Extinction was a mass extinction that occurred 270 million years ago in the Early Guadalupian of the Permian period and which predated the Permian–Triassic extinction event.[1]
Extinction Patterns
The first evidence of extinction came when Everett C. Olson noted a hiatus between Early Permian faunas dominated by pelycosaurs and therapsid dominated faunas of the Middle and Late Permian. First considered to be a preservational gap in the fossil record, the event was dubbed 'Olson's Gap'.[2][3]
Then, during the 1990s and 2000s researchers gathered evidence on the biodiversity of plants, marine organism and tetrapods that indicated an extinction pulse preceding the Permian–Triassic extinction event had a profound impact on life on land. Sahney and Benton [1] confirmed that there was a significant drop in the biodiversity of vertebrates during Olson's Extinction both on a global scale and community level. Furthermore, they showed that even discounting the sparse fossil assemblages from the extinction period, the event can be confirmed by the stages of time bracketing the event since well preserved sections of the fossil record from both before and after the event have been found.
Recovery
Fauna did not recover fully from Olson's Extinction before the impact of the Permian-Triassic extinction event. Estimates of recovery time vary, where some authors indicated recovery was prolonged, lasting 30 million years into the Triassic.[1]
Several important events took place during Olson's Extinction, most notably the origin of therapsids, a group that includes the evolutionary ancestors of mammals. Further research on the recently identified primitive therapsid of the Xidagou Formation (Dashankou locality) in China of Roadian age may provide more information on this topic.[4]
Current Relevance
A future extinction event, specifically due to anthropogenic changes, has been hypothesized by a number of scientific and environmental groups. Various possible causes include climate change, pollution, and habitat destruction. This is of great concern, due to the loss of biomes, the resources within them, and possible extinction of animal species. A better understanding of the process of extinction in the past may help determine the best course of action to preserve similar ecosystems today. Examining the conditions that led to the Olson's Extinction and the Permo-Triassic Extinction and the recovery of ecosystem from these events, may help contribute suitable solutions to resolving the current hypothetical crisis.
References
- ^ a b c
Sahney, S.; Benton, M.J. (2008). "Recovery from the most profound mass extinction of all time" (PDF). Proceedings of the Royal Society: Biological. 275 (1636): 759. doi:10.1098/rspb.2007.1370. PMC 2596898. PMID 18198148.
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Lucas, S. G. (2004). "A global hiatus in the Middle Permian tetrapod fossil record" (PDF). Stratigraphy. 1: 47–64.
{{cite journal}}: Invalid|ref=harv(help) - ^ Ivakhnenko, M. F. (2005). "Comparative survey of Lower Permian tetrapod faunas of eastern Europe and South Africa". Paleontological Journal. 39 (1): 66–71.
{{cite journal}}: Invalid|ref=harv(help) - ^ Liu, B; Rubidge; Li, J. (2009). "New basal synapsid supports Laurasian origin for therapsids" (PDF). Acta Palaeontologica Polonica. 54 (3): 393–400. doi:10.4202/app.2008.0071.
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