An extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriids

Abstract The notable disparity of animal body plans can be traced back to the morphological innovations during the Cambrian explosion and represented by a number of soft-bodied and skeletal fossils that provide a compelling narrative for animal evolution. Chancelloriids are an extinct group of Cambr...

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Main Authors: Hao Yun, Xingliang Zhang, Glenn A. Brock, Jian Han, Luoyang Li, Bing Pan, Guoxiang Li, Joachim Reitner
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Communications Biology
Online Access:https://doi.org/10.1038/s42003-025-08655-y
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author Hao Yun
Xingliang Zhang
Glenn A. Brock
Jian Han
Luoyang Li
Bing Pan
Guoxiang Li
Joachim Reitner
author_facet Hao Yun
Xingliang Zhang
Glenn A. Brock
Jian Han
Luoyang Li
Bing Pan
Guoxiang Li
Joachim Reitner
author_sort Hao Yun
collection DOAJ
description Abstract The notable disparity of animal body plans can be traced back to the morphological innovations during the Cambrian explosion and represented by a number of soft-bodied and skeletal fossils that provide a compelling narrative for animal evolution. Chancelloriids are an extinct group of Cambrian animals characterized by a distinctive sclerite-bearing, flexible integument and a single apical opening leading into a central cavity devoid of unequivocal internal organs. Their phylogenetic position within the Metazoa remains controversial. Here we show new exceptionally-preserved fossils from the 518-million-year-old Chengjiang biota of China, which corroborate the unique bauplan pattern of chancelloriids, and reveal exquisite integument microstructures including tiny protuberances and associated wrinkle-like structures that are interpreted to be related to epithelial contractions. A phylogenetic study assessing the interrelationship of chancelloriids among metazoans using modern cladistic methods is conducted to the best of our knowledge. The result suggests that chancelloriids constitute an evolutionary clade branched above and close to the Placozoa. Therefore, the enigmatic Cambrian chancelloriids represent an extinct, phylum-level basal Epitheliozoa and stem-group Eumetazoa. Their body plan has filled one of the anatomical gaps between the Placozoa and living eumetazoans within the evolutionary tree of animals.
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spelling doaj-art-e1e9e1a26b85473fb139dd0fcd6ab12d2025-08-20T04:03:00ZengNature PortfolioCommunications Biology2399-36422025-08-018111010.1038/s42003-025-08655-yAn extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriidsHao Yun0Xingliang Zhang1Glenn A. Brock2Jian Han3Luoyang Li4Bing Pan5Guoxiang Li6Joachim Reitner7State Key Laboratory of Continental Evolution and Early Life, Shaanxi Key Laboratory of Early Life and Environments, and Department of Geology, Northwest UniversityState Key Laboratory of Continental Evolution and Early Life, Shaanxi Key Laboratory of Early Life and Environments, and Department of Geology, Northwest UniversitySchool of Natural Sciences, Macquarie UniversityState Key Laboratory of Continental Evolution and Early Life, Shaanxi Key Laboratory of Early Life and Environments, and Department of Geology, Northwest UniversityKey Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, and College of Marine Geosciences, Ocean University of ChinaState Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of SciencesState Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of SciencesDepartment of Geobiology, Centre of Geosciences, University of GöttingenAbstract The notable disparity of animal body plans can be traced back to the morphological innovations during the Cambrian explosion and represented by a number of soft-bodied and skeletal fossils that provide a compelling narrative for animal evolution. Chancelloriids are an extinct group of Cambrian animals characterized by a distinctive sclerite-bearing, flexible integument and a single apical opening leading into a central cavity devoid of unequivocal internal organs. Their phylogenetic position within the Metazoa remains controversial. Here we show new exceptionally-preserved fossils from the 518-million-year-old Chengjiang biota of China, which corroborate the unique bauplan pattern of chancelloriids, and reveal exquisite integument microstructures including tiny protuberances and associated wrinkle-like structures that are interpreted to be related to epithelial contractions. A phylogenetic study assessing the interrelationship of chancelloriids among metazoans using modern cladistic methods is conducted to the best of our knowledge. The result suggests that chancelloriids constitute an evolutionary clade branched above and close to the Placozoa. Therefore, the enigmatic Cambrian chancelloriids represent an extinct, phylum-level basal Epitheliozoa and stem-group Eumetazoa. Their body plan has filled one of the anatomical gaps between the Placozoa and living eumetazoans within the evolutionary tree of animals.https://doi.org/10.1038/s42003-025-08655-y
spellingShingle Hao Yun
Xingliang Zhang
Glenn A. Brock
Jian Han
Luoyang Li
Bing Pan
Guoxiang Li
Joachim Reitner
An extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriids
Communications Biology
title An extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriids
title_full An extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriids
title_fullStr An extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriids
title_full_unstemmed An extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriids
title_short An extinct clade of the basal Epitheliozoa: phylogenetic position and implication of the enigmatic Cambrian chancelloriids
title_sort extinct clade of the basal epitheliozoa phylogenetic position and implication of the enigmatic cambrian chancelloriids
url https://doi.org/10.1038/s42003-025-08655-y
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