Chickasha Formation

{{Short description|Geologic formation in Oklahoma, United States}}

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| name = Chickasha Formation

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| type = Formation

| age = {{fossilrange|Roadian}}

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| namedfor = Chickasha, Grady County, Oklahoma

| namedby = Charles Newton Gould, 1924{{cite journal |last1=Gould |first1=Charles N. |title=A new classification of the Permian redbeds of southwestern Oklahoma |journal=American Association of Petroleum Geologists Bulletin |date=1924 |volume=8 |issue=3 |pages=322–341}}

| region = Oklahoma

| country = United States

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|period=Roadian}}

The Chickasha Formation, which is part of the El Reno Group, is a geologic formation in Oklahoma. It preserves fossils dating back to the Roadian stage of the Middle Permian.{{Cite journal |last=Laurin |first=Michel |last2=Hook |first2=Robert W. |date=2022 |title=The age of North America’s youngest Paleozoic continental vertebrates: a review of data from the Middle Permian Pease River (Texas) and El Reno (Oklahoma) Groups |url=https://www.bsgf.fr/10.1051/bsgf/2022007 |journal=BSGF - Earth Sciences Bulletin |volume=193 |pages=10 |doi=10.1051/bsgf/2022007 |issn=1777-5817|doi-access=free }} These include, among others, the dissorophoid temnospondyl Nooxobeia gracilis,{{cite journal |last1=Gee |first1=Bryan M. |last2=Scott |first2=Diane |last3=Reisz |first3=Robert R. |title=Reappraisal of the Permian dissorophid Fayella chickashaensis |journal=Canadian Journal of Earth Sciences |date=October 2018 |volume=55 |issue=10 |pages=1103–1114 |doi=10.1139/cjes-2018-0053}} the lepospondyl Diplocaulus parvus (Amphibia: Nectridea),{{cite journal |last1=Olson |first1=Everett C. |title=Diplocaulus parvus n. sp. (Amphibia: Nectridea) from the Chickasha Formation (Permian: Guadalupian) of Oklahoma |journal=Journal of Paleontology |date=1972 |volume=46 |issue=5 |pages=656–659 |url=https://www.jstor.org/stable/1303021 |issn=0022-3360}} and the captorhinid Rothianiscus robusta, initially called Rothia robusta by Everett C. Olson.{{cite journal |last1=Olson |first1=E. C. |title=New Permian Vertebrates from the Chickasha Formation in Oklahoma |journal=New Permian Vertebrates from the Chickasha Formation in Oklahoma |date=1965 |volume=70 |pages=1-70}} Many of these fossils were indicated to have come from the Flowerpot Shale, but these actually come from the Chickasha Formation, according to the current nomenclature.{{cite journal |last1=Smith |first1=Gary E. |title=Depositional systems, San Angelo Formation (Permian), north Texas--facies control of red-bed copper mineralization |journal=Report of Investigations, Bureau of economic geology |date=1974 |volume=80 |pages=73 |doi=10.26153/tsw/4807 |url=http://dx.doi.org/10.26153/tsw/4807 |language=en}} The age of the formation was long debated because Olson based part of his argument on fragmentary fossils that he interpreted as therapsids, an interpretation that was not widely accepted.{{cite journal |last1=Olroyd |first1=Savannah L. |last2=Sidor |first2=Christian A. |title=A review of the Guadalupian (middle Permian) global tetrapod fossil record |journal=Earth-Science Reviews |date=1 August 2017 |volume=171 |pages=583–597 |doi=10.1016/j.earscirev.2017.07.001 |url=http://dx.doi.org/10.1016/j.earscirev.2017.07.001 |issn=0012-8252}} Worse, one of them, Watongia,{{cite journal |last1=Olson |first1=E.C. |year=1974 |title=On the Source of Therapsids |journal=Annals of the South African Museum |volume=64 |pages=27–46 |url=https://www.biodiversitylibrary.org/page/40912017}} was later shown to be a varanopid.{{cite journal |last1=Reisz |first1=Robert R |last2=Laurin |first2=Michel |title=A reevaluation of the enigmatic Permian synapsid Watongia and of its stratigraphic significance |journal=Canadian Journal of Earth Sciences |date=1 April 2004 |volume=41 |issue=4 |pages=377–386 |doi=10.1139/e04-016 |url=https://doi.org/10.1139/e04-016 |language=en |issn=0008-4077}}