Saccorhytus is an early ecdysozoan and not the earliest deuterostome

Yunhuan Liu, Emily M Carlisle, Huaqiao Zhang*, Ben Yang, Michael Steiner, Tiequan Shao, Baichuan Duan, Federica Marone, Shuhai Xiao*, Philip C J Donoghue*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)
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The early history of deuterostomes, the group composed of the chordates, echinoderms and hemichordates, is still controversial, not least because of a paucity of stem-representatives to these clades. The early Cambrian microscopic animal Saccorhytus coronarius was interpreted as an early deuterostome on the basis of purported pharyngeal openings, providing evidence for a meiofaunal ancestry and an explanation for the temporal mismatch between palaeontological and molecular clock timescales of animal evolution. Here we report new material of Saccorhytus coronarius, which is reconstructed as a millimetric and ellipsoidal meiobenthic animal with spinose armor and a terminal mouth but no anus. Purported pharyngeal openings in support of the deuterostome hypothesis are shown to be taphonomic artifacts. Phylogenetic analyses indicate that Saccorhytus coronarius belongs to total-group Ecdysozoa, expanding the morphological disparity and ecological diversity of early Cambrian ecdysozoans.
Original languageEnglish
Pages (from-to)541-546
Number of pages6
Issue number7927
Publication statusPublished - 17 Aug 2022

Bibliographical note

Funding Information:
This work was supported by National Natural Science Foundation of China (nos. 41872014, 42172020 and 41972026, Research Fund for International Senior Scientists 2021), Strategic Priority Research Program of Chinese Academy of Sciences (no. XDB26000000), State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences (no. 20191104). E.C. was supported by a University of Bristol Scholarship; M.S. was funded by Deutsche Forschungsgesellschaft (STE814/5-1); S.X. was supported by the U.S. National Science Foundation (EAR-2021207); P.C.J.D. was funded by Natural Environment Research Council (NERC) grant (NE/P013678/1), part of the Biosphere Evolution, Transitions and Resilience (BETR) programme, which is co-funded by the Natural Science Foundation of China (NSFC), as well as the Leverhulme Trust (RF-2022-167). We acknowledge the Paul Scherrer Institut, Villigen, Switzerland for provision of synchrotron radiation beamtime at the TOMCAT beamline of the SLS. We thank D. Yang for assistance with artistic reconstructions and F. Dunn for data that contributed to our phylogenetic analyses.

Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature Limited.


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