Letter | Published:

Meiofaunal deuterostomes from the basal Cambrian of Shaanxi (China)

Nature volume 542, pages 228231 (09 February 2017) | Download Citation


Deuterostomes1 include the group we belong to (vertebrates) as well as an array of disparate forms that include echinoderms2, hemichordates3 and more problematic groups such as vetulicolians4 and vetulocystids5. The Cambrian fossil record is well-populated with representative examples, but possible intermediates6,7 are controversial and the nature of the original deuterostome remains idealized. Here we report millimetric fossils, Saccorhytus coronarius nov. gen., nov. sp., from an Orsten-like Lagerstätte from the earliest Cambrian period of South China, which stratigraphically are amongst the earliest of deuterostomes. The bag-like body bears a prominent mouth and associated folds, and behind them up to four conical openings on either side of the body as well as possible sensory structures. An anus may have been absent, and correspondingly the lateral openings probably served to expel water and waste material. This new form has similarities to both the vetulicolians4 and vetulocystids5 and collectively these findings suggest that a key step in deuterostome evolution was the development of lateral openings that subsequently were co-opted as pharyngeal gills2,3,4,8. Depending on its exact phylogenetic position, the meiofaunal habit of Saccorhytus may help to explain the major gap between divergence times seen in the fossil record and estimates based on molecular clocks9.

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Supported by Natural Science Foundation of China (nos 41621003, 41272019, 41572017, 41672009), Ministry of Science and Technology of China (D.S., J.H.) (no. 2013CB835002), Alexander von Humboldt Foundation (Q.O.), Program for New Century Excellent Talents, Ministry of Education of China (Q.O.), Department of Earth Sciences, University of Cambridge and St. John’s College, Cambridge (S.C.M.). We thank V. Brown, J. Luo, J. Sun, M. Cheng, and H. Gong for technical assistance and D.-H. Yang for the reconstruction.

Author information


  1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China

    • Jian Han
    •  & Degan Shu
  2. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK

    • Simon Conway Morris
  3. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China

    • Qiang Ou
  4. Department of Zoology, University of Kassel, Kassel 34132, Germany

    • Qiang Ou
  5. College of Petroleum Engineering, Xi’an Shiyou University, Xi’an 710065, China

    • Hai Huang


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J.H. and D.S. conceived the project. J.H., S.C.M. and Q.O. wrote early drafts of paper and assessed initial results. J.H. prepared photographs and phylogenetic analysis. H.H. undertook computerized tomography restoration. All authors discussed results, and developed observations and conclusions.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Simon Conway Morris or Degan Shu.

Reviewer Information Nature thanks A. Hejnol, I. Rahman and J. Vannier for their contribution to the peer review of this work.

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    Supplementary Information

    This file contains Supplementary Table 1 and Supplementary Data.


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