Cyclurus

Cyclurus (Ancient Greek for "rounded tail") is an extinct genus of freshwater amiid ray-finned fish known from the Late Cretaceous to the Early Oligocene across much of the Northern Hemisphere. It is thought to be the closest relative of the extant bowfins in the genus Amia, although species of Cyclurus were significantly smaller in size compared to Amia.

Cyclurus (Ancient Greek for "rounded tail") is an extinct genus of freshwater amiid ray-finned fish known from the Late Cretaceous to the Early Oligocene across much of the Northern Hemisphere. It is thought to be the closest relative of the extant bowfins in the genus Amia, although species of Cyclurus were significantly smaller in size compared to Amia. †C. efremovi (Sytchevskaya, 1981) - late Paleocene of Mongolia (Naran Bulak Formation) (=Amia efremovi Sytchevskaya, 1981 ). Named for Ivan Yefremov. †C. fragosus (Jordan, 1927) - Late Cretaceous (Maastrichtian) of Alberta, Canada (Scollard Formation) and Montana, North Dakota, South Dakota and Wyoming, USA (Hell Creek Formation, Fox Hills Formation) (=Kindleia fragosa Jordan, 1927 ) †C. gurleyi (Romer & Fryxell, 1928) - early Eocene (Ypresian) of Wyoming, USA (Fossil Butte of Green River Formation) (=†Paramiatus gurleyi Romer & Fryxell, 1928 ) †C. ignotus (Blainville, 1818) - late Eocene (Priabonian) of France (Montmartre) (=†"Amia" ignota Blainville, 1818 ) †C. macrocephalus Reuss, 1844 - middle-late Eocene of the Czech Republic (Kutschlin) †C. oligocenicus Winkler, 1880 - early Oligocene (Rupelian) of Germany (Sieblos) †C. orientalis Chang, Wang & Wu, 2010 - early-mid Eocene of Hunan, China (Xiawanpu Formation) †C. kehreri (Andreae, 1893) - middle Eocene (Lutetian) of Germany (Messel Formation & Geiseltal Formation) (=Amia kehreri Andreae, 1893 ) †C. valenciennesi Agassiz, 1844 - late Paleocene of France (Puy de Dôme of Menat Formation). Named for Achille Valenciennes. |left The species †C. "lacus" (Russell, 1928) (=†Stylomyleodon lacus Russell, 1928 ) from the middle Paleocene of Alberta, †C. "chinzhalensis" (Sytchevskaya, 1986) (=†Amia chinzhalensis Sytchevskaya, 1986 ) from the mid-late Eocene of Kazakhstan, and †C. "russelli" (Janot, 1966) (=†"Amia" russelli Janot, 1966 ) from the late Paleocene of France are considered nomina dubia due to insufficiently diagnostic remains. The Geiseltal specimens of C. kehreri differ morphologically from the Messel ones, and may represent a distinct species. Indeterminate Cyclurus remains are known from the middle Eocene of Jilin, China, the late Paleocene Ravenscrag Formation of Saskatchewan & the Maastrichtian Horseshoe Canyon Formation of Alberta, Canada, and possibly the Campanian-aged Aguja Formation of Texas, USA.

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