牙形石动物分类归属研究新进展──牙形石是最早的脊椎动物

NEW ADVANCES IN AFFINITY OF CONODONTS──THE EARLIEST VERTEBRATES

在简要回顾牙形石动物分类位置研究历史的基础上，主要介绍了近十年来这一问题的最新研究成果。英国古生物学家们通过牙形石动物的软体解剖学研究，发现眼睛、脊索、神经索、肌肉组织、尾鳍等软组织；牙形石分子硬体组织学研究揭示了细胞状骨骼、球状钙化软骨、类珐琅质及牙质等硬组织。新的证据表明牙形石动物是脊椎动物，从而将脊椎动物的历史向前推移了４０～５０Ｍａ。

Based on a brief review of the history of the biological affinites of conodonts, this paper mainly deals with the up-to-date evidence made by British conodontists on this subject. The soft anatomy of conodont shows some soft tissues including eyes, notochord, nerve cord, myomeres and caudal fin. The histological investigations into microstructure and ultrastructure of the conodont elements have been made to identify a number of hard tissues such as cellular bone, enamel homologs, globular calcified cartilage and dentine. New evidence of soft anatomy and histolgical study of conodont elements have showed that conodonts are vertebrates. In this sense, the earliest occurence of vertebrate was extended back in time by 40-50Ma.