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记述了弓鳍鱼亚科一新种:Cyclurus orientalis(东方圆尾鱼),标本采集于中国湖南省湘乡市下湾铺早始新世至中始新世下湾铺组。化石因具有以下特征而被归入弓鳍鱼亚科(Ami-inae):尾前椎为双椎型;除第一尾椎和第一尾下骨外,其余尾椎和尾下骨均一对一愈合;无膜质尾骨;背鳍长。因其第一冠状骨上的牙齿顶端圆钝,而被归入Cyclurus属。本新种与Cy-clurus属中其他种的区别在于:背鳍鳍条较少;身体短而高;脊椎和椎体较少。在始新世淡水鱼类的跨太平洋分布达到鼎盛时,由于弓鳍鱼亚科并非仅分布于太平洋两岸的类群,因此不能作为跨太平洋分布的指示类群。弓鳍鱼亚科在北半球的分布范围更广,与某些其他淡水鱼类群例如狗鱼科(Esocidae)和骨舌鱼科(Osteoglossidae)相似,这种现象只能用有别于形成跨太平洋分布的地质背景来解释。
A new species of the subfamily of the genus Arctiidae is described: the Cyclurus orientalis (Oriental round-tailed fish) was collected from Xiaobei shop in Xiaxiangpu, Hunan province from early Eocene to middle Eocene Xiaopewan. Fossils are classified as Ami-inae by virtue of the following characteristics: Anteroposterior vertebrae are of a double vertebra type; all but the first caudal vertebra and the first caudal bone, the other caudal and caudal A healing; no membranous coccyx; dorsal fin length. Due to its first coronal bilobal top blunt, and is classified as Cyclurus genus. The difference between this new species and other species in the genera Cy-clurus is that there are fewer dorsal fin rays, shorter and higher bodies, fewer spines and vertebrae. As the trans-Pacific distribution of Eocene freshwater fish reaches its peak, it can not be used as an indicator of trans-Pacific distribution because it is not only distributed across the Pacific. The subfamily Arctrotina is distributed more widely in the northern hemisphere. Similar to some other freshwater fish species such as the species Esocidae and Osteoglossidae, this phenomenon can only be described in terms of differences from the transatlantic Distribution of geological background to explain.