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.[2] These include, among others, the dissorophoidtemnospondylNooxobeia gracilis,[3] the lepospondylDiplocaulus parvus (Amphibia: Nectridea),[4] and the captorhinidRothianiscus robusta, initially called Rothia robusta by Everett C. Olson.[5] 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.[6] 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.[7] Worse, one of them, Watongia,[8] was later shown to be a varanopid.[9]
^Gould, Charles N. (1924). "A new classification of the Permian redbeds of southwestern Oklahoma". American Association of Petroleum Geologists Bulletin. 8 (3): 322–341.
^Gee, Bryan M.; Scott, Diane; Reisz, Robert R. (October 2018). "Reappraisal of the Permian dissorophid Fayella chickashaensis". Canadian Journal of Earth Sciences. 55 (10): 1103–1114. doi:10.1139/cjes-2018-0053.
^Olson, E. C. (1965). "New Permian Vertebrates from the Chickasha Formation in Oklahoma". New Permian Vertebrates from the Chickasha Formation in Oklahoma. 70: 1–70.