Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period
Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period
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DOI：
10.1038/s41467-019-13882-z
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发表时间：
2020-01
影响因子：
16.6
通讯作者：
J. Schiffbauer;T. Selly;Sarah M. Jacquet;R. Merz;L. Nelson;Michael Strange;Yaoping Cai;E. F. Smith-E.-F.-S
中科院分区：
文献类型：
--
作者：
J. Schiffbauer;T. Selly;Sarah M. Jacquet;R. Merz;L. Nelson;Michael Strange;Yaoping Cai;E. F. Smith-E.-F.-S
埃迪卡拉纪末期的化石记录以标志性的Cloudina及其近亲化石为代表。这些管栖动物被认为是原始的后生动物，但解决它们的系统发育身份仍然是一个争议点。问题的根源在于缺乏诊断特征；也就是说，系统发育解释主要集中在唯一可用的信息来源--它们的外管。在这里，通过对美国内华达州伍德峡谷地层的化石进行断层分析，我们报告了在其外管中可识别的软组织的证据。尽管另一种解释是可信的，但这些内部圆柱形结构可能被最恰当地解释为消化系统，这将是迄今为止化石记录中最早出现这种特征的地方。如果这种解释是正确的，它们的单向穿透性质不仅为将这些化石确定为确定的双边动物提供了证据，而且还对更广泛的云状动物长期争论的系统发育地位产生了影响。
The fossil record of the terminal Ediacaran Period is typified by the iconic index fossilCloudinaand its relatives. These tube-dwellers are presumed to be primitive metazoans, but resolving their phylogenetic identity has remained a point of contention. The root of the problem is a lack of diagnostic features; that is, phylogenetic interpretations have largely centered on the only available source of information—their external tubes. Here, using tomographic analyses of fossils from the Wood Canyon Formation (Nevada, USA), we report evidence of recognizable soft tissues within their external tubes. Although alternative interpretations are plausible, these internal cylindrical structures may be most appropriately interpreted as digestive tracts, which would be, to date, the earliest-known occurrence of such features in the fossil record. If this interpretation is correct, their nature as one-way through-guts not only provides evidence for establishing these fossils as definitive bilaterians but also has implications for the long-debated phylogenetic position of the broader cloudinomorphs.