Lower Cambrian vertebrates from south China
Lower Cambrian vertebrates from south China
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DOI：
10.1038/46965
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发表时间：
1999-11
期刊：
影响因子：
64.8
通讯作者：
D. Shu;Hl Luo;S. Morris;X-L. Zhang;S-X. Hu;L. Chen;J. Han;M. Zhu;Y. Li;L-Z. Chen
中科院分区：
文献类型：
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作者：
D. Shu;Hl Luo;S. Morris;X-L. Zhang;S-X. Hu;L. Chen;J. Han;M. Zhu;Y. Li;L-Z. Chen
第一个脊索动物化石是在寒武纪（距今 545-4.9 亿年前）的沉积物中发现的，但它们最早的记录非常零星，并且经常存在争议。因此，很难为基础脊索动物构建连贯的系统发育综合。到目前为止，可用的软体遗骸几乎全部由来自伯吉斯页岩型动物群的头索类动物组成。无颌鱼类的明确例子直到下奥陶世（∼475 Myr BP）才出现，而更可疑的记录延伸到寒武纪。因此，从下寒武统澄江化石-Lagerstätte 中发现两种不同类型的无颌类动物，是对其范围的非常重要的扩展。一种类似于七鳃鳗，而另一种则更接近更原始的盲鳗。这些发现表明，第一批无颌动物可能是在最早的寒武纪进化而来的，而脊索动物则起源于埃迪卡拉时代（最近的新元古代，约 555 Myr BP）甚至更早的更原始的后口动物。
The first fossil chordates are found in deposits from the Cambrian period (545–490 million years ago), but their earliest record is exceptionally sporadic and is often controversial. Accordingly, it has been difficult to construct a coherent phylogenetic synthesis for the basal chordates. Until now, the available soft-bodied remains have consisted almost entirely of cephalochordate-like animals from Burgess Shale-type faunas. Definite examples of agnathan fish do not occur until the Lower Ordovician (∼475 Myr BP), with a more questionable record extending into the Cambrian. The discovery of two distinct types of agnathan from the Lower Cambrian Chengjiang fossil-Lagerstätte is, therefore, a very significant extension of their range. One form is lamprey-like, whereas the other is closer to the more primitive hagfish. These finds imply that the first agnathans may have evolved in the earliest Cambrian, with the chordates arising from more primitive deuterostomes in Ediacaran times (latest Neoproterozoic, ∼555 Myr BP), if not earlier.