关于晚二叠世克氏蛤类研究中的几个问题  

DISCUSSION ON THE STUDY OF THE GENERA CLARAIA AND CLARAIOIDES (BIVALVIA) OF LATE PERMIAN AGE

作　　者：方宗杰[1] 

机构地区：[1]中国科学院南京地质古生物研究所,南京210008

出　　处：《古生物学报》2003年第4期613-619,共7页Acta Palaeontologica Sinica

基　　金：国家重大基础研究发展规则项目 (G2 0 0 0 7770 8)

摘　　要：对当前二叠 三叠纪克氏蛤类研究中存在的几个问题进行讨论 ,并对杨逢清等 (2 0 0 2 )提出的关于属一级划分的原则提出质疑。通过对Claraiatumida(Patte)的再研究 ,确认早三叠世的克氏蛤不存在足丝凹口内端呈明显扩大的类型。经过详细的讨论和比较 ,无论是从形态上 ,或是生态上 ,还是从生物地理学的角度 ,克氏蛤和类克氏蛤在晚二叠世都应被视为两个平行发展的属。类克氏蛤在二叠纪末全部灭绝 ,未留下任何后裔 ,它与克氏蛤之间并不存在演化关系。克氏蛤的地质历程是晚二叠世早期至早三叠世晚期 ,发现于俄罗斯北极区新地岛晚二叠世早期的ClaraianovosemelicaLobanova是克氏蛤的最早代表 ,它应当位于克氏蛤演化的基干部位。There have been some different opinions on the classification of the Permo Triassic Claraias (Zhang, 1980; Fang, 1993; Newell and Boyd, 1995; Yang et al ., 2002; Chen and Komatsu, 2002). Yang and co workers (2002) laid undue stress on the importance of dentition for generic assignment in Claraias and confused both “anodont” and “isodont” of scallops with “dysodont”. In fact, the dentition is all nonsense for the classification of Claraias, since all of Claraias are edentulous. The byssal notch of Triassic Claraia tumida (Patte) ( =Pseudomonotis speluncaria var. tumida Patte, 1935, p.22, pl.2, figs. 2—6) was mistaken by Yang et al (2002, Fig. 2b) for a Claraioides type because the byssal notch illustrated by Patte (1935) on figure 4 of plate 4 is evidently broken (text fig. 1: 2, 5, 7). The other specimens (Patte, 1935, pl. 2, figs. 3, 5, 6) are much better preserved and show perfectly the typical Claraia type byssal notch. The specimen illustrated by Patte (1935) on figure 5 of plate 2 is here selected as the lectotype of the species Claraia tumida (Patte) (text fig. 1∶3). All species of the genus Claraioides , including C. primitivus (Yin), 1983, C. dianus (Guo), 1985, C. praecursor (Wu et Hong), 1991, C. guizhouensis Fang, 1993, C. zhiyunensis (Yang, Gao et Peng), 2002, have a subcircular byssal embayment in the right valve (lower valve), which is quite different from the slit like or distally contracted byssal notch of the genus Claraia Bittner, 1901. Among them, C. guizhouensis Fang has no radial ornaments occurring in the early Late Permian (Wujiapingian), and the rest of the species appeared in the Changxingian. According to Chen and Komatsu (2002), the genus name Pseudoclaraia Zhang, 1980 is a junior synonym of Claraia Bittner, 1901. Thus Claraia novosemelica Lobanova (= Pseudomonotis permiana of Lutkevich and Lobanova, 1960; = Pseudoclaraia siberiensis Zhang, 1980) from the Dzhulfian of Novaya

关 键 词：晚二叠世 克氏蛤类 双壳类 华南 类克氏蛤 

分 类 号：Q915[天文地球—古生物学与地层学]