云南文山早泥盆世盔甲鱼类的新发现

NEW DISCOVERY OF GALEASPIDS FROM EARLY DEVONIAN OFWENSHAN, SOUTHEASTERN YUNNAN, CHINA

描述了采自云南东南部文山地区下泥盆统坡松冲组下部的无颌类化石,建立了盔甲鱼类的一新属、新种──纸厂文山鱼(Ｗｅｎｓｈａｍｐｉｓ ｚｈｉｃｈａｎｇｓｉｓ ｇｅｎ．ｅｔ ｓｐ．ｎｏｖ．),同时修订了两个盔甲鱼类的旧属、旧种──长吻三歧鱼(Ｓａｎｑｉａｐｉｓ ｒｏｓｔｒａｔａ)及长角大窗鱼(Ｍａｃｒｏｔｈｙｒａｓｐｉｓｌｏｎｇｉｃｏｒｎｉｓ)。迄今为止,长吻三歧鱼仅在四川江油雁门坝的平驿铺组中部发现并记述过,长角大窗鱼也仅有一件采自云南广南坡松冲组中的正型标本,而纸厂文山鱼为滇东南文山地区首次记述的多鳃鱼类新属种,它与滇东北昭通地区下泥盆统坡松冲组中的让氏昭通鱼(Ｚｈａｏ－ｔｏｎｇａｓｉｓ ｊａｎｖｉｅｒｉ)最为相似。此次这三个盔甲鱼类属种在滇东南文山地区的发现,为该区下泥盆统的横向对比提供了重要的古鱼类学方面的证据。

The Lower Devonian strata of the Wenshan District in southeastern Yunnan are well exposed and can be subdivided into Posongchong, Pojiao and Bajiaoqing formations in ascending order.As a typical non-marine stratum, the Posongchong Formation bears abundant fossils of plants, spores and early vertebrates, including antiarchs, sarcopterygians and galeaspids such as Kwangnanaspis sub-triangularis (Cao, 1979), Gantarostrataspis gengi, Gumuaspis rostrata (Wang and Wang, 1992)and Macrothyraspis longicornis (Pan, 1992). Recently, new galeaspid specimens were collected from the lower part of the Posongchong Formation in Gumu, Wenshan ( Fig. 1) . They are referred to Wenshanaspis zhichangensis gen. et sp. nov. , Sanqiaspis rostrata (Liu, 1975) and M. longicornis (Pan, 1992) respectively. All of these fossils show that the Posongchong Formation is of Pragian in age, like the Xujiachong Formation in Qujing, eastern Yunnan and the Pingyipu Formation in Jiang-you, Sichuan. Gantarostrataspis gengi and Sanqiaspis rostrata exclusively found in these three re-gions indicate their biogeographic connection.