地学前缘 ›› 2020, Vol. 27 ›› Issue (6): 79-103.DOI: 10.13745/j.esf.sf.2020.6.4

• 早期生命演化 • 上一篇    下一篇

华南寒武纪碳酸盐岩中最早腕足动物的辐射、发育与分布

张志亮1,2(), 陈飞扬1,2, 张志飞1,*()   

  1. 1.西北大学 地质学系 大陆动力学国家重点实验室与早期生命与环境陕西省重点实验室, 陕西 西安 710069
    2.麦考瑞大学生命科学系, 澳大利亚 悉尼 NSW 2109
  • 收稿日期:2020-03-23 修回日期:2020-05-27 出版日期:2020-11-02 发布日期:2020-11-02
  • 通讯作者: 张志飞
  • 作者简介:张志亮(1988—),男,博士,主要从事寒武纪早期壳体化石形态、结构与发育研究。E-mail:zhiliang. zhang@mq.edu.au
  • 基金资助:
    国家自然科学基金项目(41425008);国家自然科学基金项目(41720104002);国家自然科学基金项目(41621003);国家自然科学基金项目(41890844);中国科学院战略性先导科技专项(B类)项目(XDB26000000);高等学校学科创新引智计划111项目(D17013);国家留学基金委公派研究生项目(CSC 201806970026);澳大利亚麦考瑞大学研究奖学金项目(Macquarie University Research Fellowships)(2019 MQRF)

The earliest phosphatic-shelled brachiopods from the carbonates of South China: their diversification, ontogeny and distribution

ZHANG Zhiliang1,2(), CHEN Feiyang1,2, ZHANG Zhifei1,*()   

  1. 1. State Key Laboratory of Continental Dynamics and Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi’an 710069, China
    2. Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
  • Received:2020-03-23 Revised:2020-05-27 Online:2020-11-02 Published:2020-11-02
  • Contact: ZHANG Zhifei

摘要:

腕足动物是寒武纪冠轮动物分支的重要类群,在寒武纪大爆发期间海洋底栖动物群落结构构建中发挥着重要作用。研究表明华南最早的腕足动物出现在寒武系第二统。通过大量酸蚀处理和系统分析,发现华南寒武纪第二世碳酸盐岩相中赋存的腕足动物可分为8属12种和3个未定属种,都属于磷酸钙质舌形贝型,揭示了寒武纪早期磷酸钙质壳腕足动物的多样性及其形态差异。通过全球对比,力求探索寒武纪最早腕足动物的起源、多样性、分布与辐射。通过个体发育研究,揭示了异时发育在乳孔贝形态多样性中发挥的重要作用,同时表明寒武纪舌形贝型腕足动物发育中普遍存在滤食型浮游幼虫和变态发育的过程。因此变态发育的浮游幼虫可能是腕足动物的祖先特征。这与现代舌形贝明显不同,现代舌形贝的浮游幼虫为次级幼虫,演变为直接发育。此外,对比全球不同大陆腕足动物的首现,认为舌形贝型亚门腕足动物可能在寒武纪第二世初起源于东冈瓦纳与华南板块,随后开始向全球扩散。对寒武纪早期腕足动物多样性、个体发育与生物地层的深入研究,有助于增进对关键动物门类的早期起源与系统演化的认识,同时也将推动全球和区域寒武纪生物地层的划分与对比。

关键词: 腕足动物, 磷酸钙质壳, 个体发育, 多样性, 寒武纪第二世, 华南

Abstract:

Brachiopoda, as a key phylum of lophotrochozoan animals, plays an important role in studying the biodiversification of benthic communities during the Cambrian evolutionary radiation. Eight genera and twelve species of brachiopods, with the exception of three indeterminate taxa, are revealed and recovered from the Cambrian Series 2 carbonate facies near the Ediacaran-Cambrian boundary in the Yangtze Platform. They represent one of the earliest assemblages or components of brachiopods from South China. Based on the brachiopod data, the shell morphology and textural structures of the earliest variety of brachiopod groups and their occurrences and dispersals are discussed here to explore the origin and biodiversification of phosphatic-shelled brachiopods. We then summarised the recent research advances on the development of Cambrian brachiopods known from the Xihaoping Member of the Dengying, Shuijingtuo, and Yu’anshan formations of the Yangtze Platform. Lines of studies demonstrated that the linguliform brachiopods achieved adaptive diversity in the ornamentation of metamorphic and mature shells and shell structures, and in the configuration of pedicle foramen during the Cambrian explosion. In addition, three ontogenetic stages, including the pedicle foramen formation stage, pedicle foramen enclosure stage, and intertrough increasing stage, are observed in Cambrian Epoch 2 acrotretides. Compared with the ontogenetic developmental processes in different genera and species of acrotretides, the post-metamorphic allometry of shell valves was recognized as it played an increasingly significant role in the morphological diversification of different acrotretide clades. Furthermore, our recent studies on the earliest ontogenetic characteristics, preserved in the metamorphic shells in the oldest known lingulides and acrotretides, demonstrated that metamorphosis of planktotrophic larva is plesiomorphic for all brachiopods while the living lingulids are modified to obtain secondary larva with direct development. Interestingly, separate and diachronous occurrences of the oldest known brachiopods in the Cambrian palaeocontinents implied that linguliform brachiopods probably originated in East Gondwana and South China during the early Cambrian Epoch 2 and achieved a cosmopolitan dispersal subsequently. More studies on the diversity, ontogeny and biostratigraphy of the earliest phosphatic-shelled brachiopods will help us improve our understanding of their origination and the evolutionary changes of different lineages to uncover the correlation of Cambrian strata in detail.

Key words: brachiopods, phosphatic-shelled, ontogeny, diversity, Cambrian Epoch 2, South China

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