关键词: 比耶鱼, 盘县动物群, 中三叠世, 贵州省

Abstract:

A large-sized caudal fin of the actinopteryigan Birgeria, from the Middle Triassic (Pelsonian, Anisian) Panxian Fauna in the Upper Member of the Guanlin Formation, Panxian County, Guizhou Province, China is described. It is the first report of Birgeria in the Panxian Fauna and represents the earliest fossil record of Birgeria in China. There are some specialized characters for this specimen in accordance with Bigeria: the speculated large size, narrow scales without ganoine ornament merely covering the posterodorsal portion of the caudal peduncle and the axial lobe of the caudal fin, single neural spine and haemal spine in caudal region, fulcra scales developed on the dorsal margin of the caudal fin, etc, which support the assignment of the current specimen to the genus Birgeria. Moreover, it distinguish from all known Birgeria species in its relatively large size (speculated total length over 2 m), a higher number of hypural (9), fulcras of the ventral margin of the caudal fin more developed and a bigger angle between the posterior margin of upper lobe and that of the lower lobe (>70º), but, a Birgeria sp. instead of a new species of Birgeria is assigned herein due to limited material. Birgeria is a kind of large carnivorous fish exsisting only in the Triassic ocean, which can be found from the Anisian Panxian Fauna to the Carnian Guanlin Fauna. The first appearance of Birgeria in China is later than that in West Tethys in Smithian, Early Triassic.

Key words: Birgeria, Panxian Fauna, Middle Triassic, Guizhou Province