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贵州中三叠世兴义生物群卢加诺鱼属(卢加诺鱼科,新鳍鱼类)一新种

发表日期:2020-06-24来源:放大 缩小

作者:徐光辉

摘要:新鳍鱼类是辐鳍鱼亚纲中最大的现生类群,中三叠世卢加诺鱼科则是新鳍鱼类干群中的一支,具有特化的头骨和特别高的侧腹鳞片。自1939年命名以来,卢加诺鱼科仅以瑞士东部和南部、意大利北部和西班牙东南部中三叠世海相地层安尼期/拉丁期界线附近发现的瓷鳞卢加诺鱼(Luganoia lepidosteoides)为唯一代表。根据贵州兴义中三叠世晚期(拉丁期)海相地层发现的一块较完整的精美鱼化石,命名了卢加诺鱼属一新种,祥瑞卢加诺鱼(Luganoia fortuna sp. nov.)。新种代表了卢加诺鱼科在亚洲的首次出现,表明此科的生物地理分布比之前认识的要大很多。基于新种与模式种的比较研究,修订了卢加诺鱼属的鉴定特征,揭示了该属过去一些未注意到的解剖学特征,例如存在一对眶前骨,缺少板片状的方颧骨,背鳍基部具有一狭长的裸露身体区域;臀鳍很小,与尾鳍的距离比与腹鳍更近;后匙骨缺失。此外,详细列举了中国新种与欧洲模式种的形态差异,研究结果为了解卢加诺鱼属的形态多样性提供了重要信息。
关键词:贵州兴义,三叠纪,卢加诺鱼科,新鳍鱼类,骨骼学,古地理

 

A new species of Luganoia (Luganoiidae, Neopterygii) from the Middle Triassic Xingyi Biota, Guizhou, China

XU Guang-Hui

Abstract  Neopterygii is the largest known group of ray-finned fishes today, and the Luganoiidae, recognized by its specialized skull and greatly deepened flank scales, is a stem lineage of this group in the Middle Triassic. Since its naming in 1939, the Luganoiidae has been represented solely by the marine species Luganoia lepidosteoides found near the Ladinian/Anisian boundary of the southern and eastern Switzerland, northern Italy and southeastern Spain. Here, I report the discovery of a new species of this genus, Luganoia fortuna sp. nov. based on a nearly complete specimen from the late Middle Triassic (Ladinian) marine deposits exposed near Xingyi, Guizhou, China. The discovery represents the first record of the Luganoiidae in Asia, indicating that the biogeographical distribution of this family is much wider than previously recognized. Comparative studies of the new species with the type species from Europe reveal some anatomical features previously unnoticed in Luganoia, e.g., the presence of antorbitals, absence of a plate-like quadratojugal, presence of a narrow naked region of the body at the base of the dorsal fin, presence of a small anal fin closer to the caudal fin than to the pelvic fin, and absence of postcleithra. An amended diagnosis of the genus is presented. Moreover, the distinguishable features between the Chinese and European species are highlighted in this study, and they provide valuable information on the morphological diversification of Luganoia.
Key words  Xingyi, Guizhou; Triassic; Luganoiidae, Neopterygii; osteology; paleobiogeography

 

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