none 10.1144/jgs2020-246 Geological Society of London Geological Society of London 1881 124220200 44798 2024111903341300279 10.1144 2024-11-19T09:04:35Z 2021-02-17T10:55:25Z 30 Journal of the Geological Society JGS 0016-7649 2041-479X 10 05 2021 09 2021 178 5 Cédric Aria State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology & Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing 210008, China https://orcid.org/0000-0002-0567-1730 Fangchen Zhao State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology & Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing 210008, China https://orcid.org/0000-0001-8473-4439 Maoyan Zhu State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology & Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing 210008, China College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China https://orcid.org/0000-0001-7327-9856 In spite of their unrivalled ecological success, the origins of terrestrial mandibulates have long remained virtually unknown. In recent years, claims have been made based on phylogenetic results that fuxianhuiids, iconic fossils of the Chengjiang biota and purported basal euarthropods, were in fact mandibulates, allied with the problematic euthycarcinoids as the closest sister-group to Mandibulata or even stem myriapods. A re-examination of euthycarcinoid mouthparts has since brought additional support to this view. Here, we reinvestigated the anterior anatomy of the Cambrian euarthropod Fuxianhuia and its relatives. We demonstrate that the fuxianhuiid head is that of a mandibulate, sharing similarities with hymenocarines, including a limbless intercalary segment. The hypostome is a sub-triangular sclerite partially fused but anatomically independent from a large, bilobed labral plate, as observed in many extant mandibulate taxa as well as euthycarcinoids. The so-called ‘specialized post-antenn(ular) appendages' are therefore the mandibles, with a tripartite palp and large dented gnathal lobe partially covered by the hypostome-labrum complex. Under a ‘deep split' phylogenetic scenario, Fuxianhuia and its relatives are here resolved as sister-group to crown Mandibulata. Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosion Supplementary material : Additional remarks on terminology, morphological interpretations and a list of modified/new characters used for the phylogenetic analysis are available at https://doi.org/10.6084/m9.figshare.c.5305042 03 22 2021 09 2021 jgs2020-246 10.1144/jgs2020-246 1 10.1144/crossmark-policy www.lyellcollection.org true 2020-12-11 2021-02-03 2021-02-12 2021-03-22 Strategic Priority Research Program (B) of the Chinese Academy of Sciences XDB26000000 National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809 41921002 State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology 20181105 National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809 42072006 https://doi.org/10.15223/policy-002 10.1144/jgs2020-246 https://www.lyellcollection.org/doi/10.1144/jgs2020-246 https://www.lyellcollection.org/doi/pdf/10.1144/jgs2020-246 https://geoscienceworld.org/jgs/article-lookup?doi=10.1144/jgs2020-246 10.1111/1475-4983.00308 10.1017/pab.2020.36 10.1371/journal.pone.0124979 10.1038/nature22080 10.1186/s12862-017-1088-7 10.1111/pala.12161 10.1186/s12862-019-1560-7 10.1080/11035890809452772 Geological Survey of Canada, Bulletin Briggs D.E.G 1 264 1976 The arthropod Branchiocaris n.gen., Middle Cambrian, Burgess Shale, British Columbia Briggs, D.E.G. 1976. 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