CAJ | 학술논문

长期以来,双壳类研究者虽未将扬子蛤(Yangtzedonta Yu)纳入到双壳类早期系统演化的研究范畴,却又难以予以完全否定.最近,钱逸的工作终于解决了这一悬案,这是寒武纪带壳软体动物研究的一项重要进展.然而,钱逸对双壳类早期演化的理解仍存在着误解,例如,将Xianfengoconcha Zhang当作是"最古老的双壳类",为此有必要对近二十年来我国寒武纪双壳类的研究进行回顾与总结.Xianfengoconcha发育有两侧对称排列的所谓"片状齿",实属腕足类小圆货贝型铰合构造.化石证据表明,真正的片状齿是由古栉齿型铰齿演化而来,因此,古异齿型不是双壳类最古老的铰齿类型.目前,我国没有争议的寒武纪双壳类只有Pojetaia Jell一属.
장기이래,쌍각류연구자수미장양자합(Yangtzedonta Yu)납입도쌍각류조기계통연화적연구범주,각우난이여이완전부정.최근,전일적공작종우해결료저일현안,저시한무기대각연체동물연구적일항중요진전.연이,전일대쌍각류조기연화적리해잉존재착오해,례여,장Xianfengoconcha Zhang당작시"최고로적쌍각류",위차유필요대근이십년래아국한무기쌍각류적연구진행회고여총결.Xianfengoconcha발육유량측대칭배렬적소위"편상치",실속완족류소원화패형교합구조.화석증거표명,진정적편상치시유고즐치형교치연화이래,인차,고이치형불시쌍각류최고로적교치류형.목전,아국몰유쟁의적한무기쌍각류지유Pojetaia Jell일속.
The genus Yangtzedonta Yu,1985 have not been accepted by bivalve specialists as a bivalve as Yu originally reported in studying early phylogeny and evolution of the class Bivalvia. Recently,Qian Yi(2001)solved this puzzle.He confirms that Y.primitiva Yu is only an incomplete specimen of Xianfengella prima He et Yang,a problematical small shelly fossil.It is a pity that Qian confused Xianfengoconcha elliptica Zhang with the oldest certain bivalve. It is necessary to review comprehensively the study of Cambrian bivalves in China.Xiangfengoconcha Zhang,1980 shows an elongate,weakly inclined anterior and posterior toothlike structure on each side of the beak.This is an obolellid type hinge structure rather than the bivalve palaeoheterodont type.Moreover lamellar teeth of palaeoheterodonts were derived from the fusion of discrete teeth of palaeotaxodont type.Therefore,it is unlikely that the most primitive bivalve was such a form with lamellar teeth as Xianfengoconcha elliptica Zhang.At present,Pojetaia Jell,1980 is the only undoubted Cambrian bivalve in China.