摘要
本文通过对近年来在广西横县六景采集的下泥盆统胴甲鱼类化石的描述,同时对以往记述或报道过的该地的胴甲鱼类化石作了简要的评说,在此基础上,列出了广西下泥盆统莲花山组的胴甲鱼类化石.根据这些胴甲鱼类化石内容,讨论了桂中南的莲花山组与滇东曲靖有关地层的对比,重申了桂中南莲花山组的地质时代应和曲靖西屯组的相当.由于直伏于西屯组之下,尚有一含多鳃鱼类化石为其特色的西山村组,该组又公认是早泥盆世早期的沉积,因此,桂中南的莲花山组之下,缺失了相当于西山村组的沉积.很显然,以莲花山组的地层内容所建立的莲花山阶,用来代表我国早泥盆世早期的沉积是不妥当的.
The Lower Devonian of China has been divided into four stages: Lianhuashan, Nakaoling, Yujiang and Shipainian in ascending order. The stratotype section of the three lower stages of them are located at Liujing, Guangxi (Hou, H. F., Wang, S. T. et al., 1988). Both Nakaoling Formation and Yujing Formation are marine sediments, yielding a large quantity of fossil invertebrates. But Lianhuashan Formation is non-marine sediment, yielding abundant fossil fishes. The fossils described and reported from Lianhuashan Formation are Asiaspis (Pan, J., 1973) of jawless vertebrate, Asiacanthus (Liu, S.-F., 1982) of Arthrodira and Kwangsilepis (Pan, J., 1973), Orientolepis, Lianhuashanolepis (Pan, J. and Wang, S.-T., 1978) and Yunnanolepis (Liu, S.-F., 1974) of Antiarchi. The antiarchians are predominant in this fish fauna, but there are questions in the identification of the genera. Kwangsilepis was erected by Pan in 1973 for a trunk-armour, whereas Yunnanolepis was erected by Liu before 10 years (Liu, Y.-H. I963) for a head-shield from E. Yunnan. Many antiarchian remains have been recovered since then from the same region of E. Yunnan. The specimens are mostly well preserved, some nearly complete trunk-armour associated with head shield in Yunnanolepis chii (Zhang, G.-R., 1978). And the anterior median dorsal plates of Yunnanolepis chii are very similar to those in Kwangsilepis kwangsiensis. Therefore, it is very possible that Kwangsilepis kwangsiensis is a synonym of Yun nanolepis chii. The erection of Lianhuashanolepis liukiangensis was based on those characters which result from reverse of the anterior median dorsal plate. In fact, the plate shows general character of that of Yunnanolepis, if put it upside down again (Zhang, 1979). The erection of Orientolepis neokwangsiensis was also based on the characters of the anterior median dorsal plate, such as egg-shaped outline, anterior ventral process developed and located at about anterior 1/4 of total armour length etc.. These characters are also in the possession of Qujinolepis. It seems to indicate that Orientolepis and Qujinolepis should be the same genus. In this paper some antiarchian fossils from Liujing, Guangxi are described (in chinese part). They belong to Yunnanolepis chii, Qujinolepis gracilis, and Zhanjilepis sp. respectively. On the basis of the description of the new antiarchian material and examination of the previously described antiarchians from Lianhuashan Formation of Liujing, Guangxi, a few points about the fauna and related problems in stratigraphy may be summerized as follows: 1) In the described antiarchians from Lianhuashan Formation of Liujing, Guangxi, only Yunnanolepis chii, Qujinolepis gracilis and Zhanjilepis sp. can be recognized. 2) The antiarchians from Lianhuashan Formation are very similar to those of Xitun For- mation in E. Yunnan. Therefore, Lianhuashan Formation should correspond roughly to Xitun Formation in age. 3) In E. Yunnan, Xitun Formation overlies conformably Xishancun Formation which yields abundant Polybranchiaspis. It is considered as the bottom of the Lower Devonian. The Lianhuashan Formation overlies unconformably Cambrian deposit, and the stratum corresponding with Xishancun Formation is absent in Guangxi. Obviously, the Lianhuashan Formation considered as sediment of the bottom part of Lower Devonian is unreasonable.
出处
《古脊椎动物学报》
CSCD
北大核心
1992年第3期210-220,257-258,共11页
Vertebrata Palasiatica
关键词
下泥分统
胴甲鱼类
广西
Guangxi
Lower Devonian
Antiarchians
