一些原牙形石、副牙形石和最早的真牙形石的组织学和比较组织学研究  

STUDY ON HISTOLOGY AND COMPARATIVE HISTOLOGY OF SOME PROTOCONODONTS,PARACONODONTS AND EARLIEST EUCONODONTS

作　　者：董熙平[1] 

机构地区：[1]北京大学地球与空间科学学院,北京100871

出　　处：《微体古生物学报》2007年第2期113-124,共12页Acta Micropalaeontologica Sinica

基　　金：国家自然科学基金委员会基金(批准号:40372001;40572003);中国科学院南京地质古生物研究所开放研究实验室基金(批准号:023106);高校博士点基金(批准号:2000000127;20060001059)的资助。

摘　　要：本文主要介绍对采自湘西、辽东和鲁西的寒武纪牙形石进行组织学和比较组织学研究成果中尚未发表的内容。以前认为是原牙形石的属Huyuanodontus的组织学构造与原牙形石、副牙形石以及真牙形石均不相同,而且与任何已知化石类群的组织学构造亦不相同。副牙形石Prooneotodus rotendatus和Prooneotodus gallatini中的一些分子具有厚薄不同的齿冠,应属于真牙形石。在已采集到的副牙形石属Laiwugnathus的所有标本中,既未发现副牙形石生长层构造,也未发现牙本质。在具有典型的副牙形石生长层构造的标本中发现了令人信服的牙本质。在最早的真牙形石Proconodontus muelleri中发现了较复杂的管状牙本质。组织学研究证实Coelocerodontus bicostatus为真牙形石。上述成果以及我国寒武纪牙形石组织学和比较组织学已经发表的成果(如:Dong,2004;Dongetal.,2005等)说明研究寒武纪牙形石必需研究牙形石组织学。目前,正在进行的寒武纪牙形石研究的两项主要工作《厘定寒武纪牙形石的分类》以及《副牙形石和早期真牙形石的谱系分析》,均是以组织学的研究为基础的。In light of oriented thin-sectioning and oil immersion （Donoghue, 1997）, protoconodonts, paraconodonts and earliest euconodonts recovered from the Cambrian strata in western Hunan, eastern Liaoning and western Shandong were investigated at the University of Birmingham, UK, by Phil Donoghue and Xi-ping Dong and at Peking University, Beijing , China, by Guichun Wu and Wei Guo in terms of histology and comparative histology. Seven papers on the results of this investigation, e.g. Dong, 2004; Dong et al. , 2005 （see references therein for other papers ） have been published. The present study focuses on the results which have been neither published nor fully illustrated. Based on the morphological anatomy, Huayuanodontus （Dong, 1993） is protoconodont. However, the histological structure of Huayuanodontus is not only different from those of protoconodonts, paraconodonts and euconodonts, but also different from those of any known fossils. The euconodont crown tissues of different thickness are found in quite a few specimens of Prooneotodus rotendatus and Prooneotodus gallatini. All the specimens of the two species had been exclusively assigned to paraconodonts before. The histological structure of Coelocerodontus bicostatus van Wamel, 1974 suggests that it is typical euconodont rather than protoconodont or paraconodont. The complex tubular dentine is found in the earliest euconodont Proconodontus muelleri Miller, 1980, whereas the atubular dentine is found in the specimen of paraconodont. All the above results demonstrate that the histological investigation is crucial to the study on Cambrian conodonts. Indeed, the two major projects： ＂Taxonomic revision of Cambrian conodonts＂ and ＂Phylogenetic analysis of paraconodonts and earliest euconodonts＂ are both based on the histological studies.

关 键 词：原牙形石 副牙形石 最早的真牙形石 组织学 比较组织学 寒武纪 

分 类 号：Q915[天文地球—古生物学与地层学]